ap物理c】真题】解答题c2000
【AP物理C】【真题】解答题C2000AP? Physics C2000 Free response QuestionsThe mat erials included in these files are intended for use by AP teachers for course and exam preparation in the classroom; permission for any other use must be sought from the Advanced Placement Program?. Teachers may reproduce them, in whole or in part, in limited quantities, for face-to-face teaching purposes but may not mass distribute the materials, electronically or ot herwise. These mat erials and any copies made of t hem may not be resold, and the copyright notices must be retained as they appear here. This permission does not apply to any third-party copyrights contained herein.These materials were produced by Educational Testing Service? (ETS?), which develops and administers the examinations of the Advanced Placement Program for the College Board. The College Board and Educational Testing Service (ETS) are dedicated to the principle of equal opportunity, and their programs, services, and employment policies are guided by that principle.The College Board is a national nonprofit membershipassociation dedicated to preparing, inspiring, and connecting students to college and opportunity. Founded in 1900, the association iscomposed of more than 4,200 schools, colleges, universities, and other educational organizations. Each year, the College Board serves over three million students and their parents, 22,000 high schools, and 3, 500 colleges, through major programs and services in college admission, guidance, assessment, financial aid, enrollment, and teaching and learning・ Among its best-known programs are the SAT?, the PSAT/NMSQT?, and the Advanced Placement Program? (AP?). The College Board is committed to the principles of equity andexcellence, and that comm it men t is embodied in allof its programs, services, activities, and concerns.API EL is a trademark owned by the College Ent rance Examination Board・ PSAT/NMSQT is a registeted trademark jointly owned by the College Entrance Examination Board and the National Merit Scholarship Corporation. Educational Testing Service and ETS are registered trademarks of Educational Testing Service.Copyright ? 2000 by College Entrance Examination Board.All rights reserved.College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registered trademarks of the College Entrance Examination Board.(2000 Ml) You are conducting an experiment to measure the acceleration due to gravity gu at an unknown location. In the measurement apparatus, a simple pendulum swings past a photogate located at the pendulum^ s lowest point, which records the time tlO for the pendulum to undergo 10 full oscillations. The pendulum consists of a sphere of mass m at the end of a st ring and has a leng th 1. There are four versions of this apparatus, each with a different length. All four are at the unknown location, and the data shown below are sent to you during the experiment.tio T T2 ? (s) (s) (s2) (cm) 12 18 21 32 a. For each pendulum, calculate the period T and the square of the period. Use a reasonable number of signifies nt figures. Enter these results in the table above.b.On the axes below, plot the square of the period versus the length of the pendulum. Draw a best-fit straight linefor this data. c. Assuming that each pendulum undergoessmall amplitude oscillations, from your fit determine the experimental value gexp of the acceleration due to gravity at this unknown location. Justify your answer.d.If the measurement apparatus allows a determination of gexp that is accurate to within 4%, is your experimentalvalue in agreement with the value m/s2 ? Justify your answer.e.Someone informs you that the experimental appara tus is in fac t neat Ear th's surface, but that the experiment hasbeen conducted inside an elevator with a constant acceleration a. Assuming that your experimental value g is exact, determine the magnitude and direction of the elevatoH s acceleration.Copyright ? 2000 by College Entrance Examination Board. All rights reserved.College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registeted trademarks of the College Entrance Examination Board.2000M2. A rubber ball of mass m is dropped from a cliff. As the ball falls, it is subject to air drag (a resistiveforce caused by the air). The drag force on the ball has magnitude bv2, where b is a constant drag coefficient and v is the instantaneous speed of the ball. The drag coeff icie nt b is direc tly proportional to the cross-sectional area of the ball and the density of the air and does not depend on the mass of the ball. As the ball falls, its speed approaches a constant value called the terminal speed.a.On the figure below, draw and label all the forces on the ball at some instant before it reaches terminal speed.b.State whether the magnitude of the acceleration of the ball of mass m increases, decreases, or remains the sameas the ball approaches terminal speed. Explain.c.Write, but do NOT solve, a differential equation for the instantaneous speed v of the ball in terms of time t, thegiven quantities, and fundamentai constants.d.Det ermine the terminal speed vt in t erms of the given quantities and fundamental constants.e.Determine the energy dissipated by the drag force during the fall if the ball is released at height h and reachesits terminal speed before hitting the ground, in terms of the given quantities and fundamental constants.2000M3・ A pulley of radius R1 and rotational inertiaII is mounted on an axle with negligible friction. A light cord passing over the pulley has two blocks of mass m attached to either end, as shown above. Assume that the cord does not slip on the pulley. Det ermine the answers to parts (a) and (b) in t erms of m, Rl, II, and fundamental constants, a. Determine the tension T in the cord.b.One block is now removed from the right and hung on the left・ When the system is released from rest, the threeblocks on the left accelerate downward with an accelera tion g/3 • Det ermine the following, i. The tension T3 in the section of cord supporting the three blocks on the left ii. The tension T1 in the section of cord supporting the single block on the right iii. The rotational inertia II of the pulleyCopyright ? 2000 by College Entrance Examination Board. All rights reserved.College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registered trademarks of the CollegeEntrance Examination Board.c.The blocks are now removed and the cord is tied into a loop, which is passed around the original pulley and asecond pulley of radius 2R1 and rotational inertia 1611. The axis of the original pulley is attached to a motor that rotates it at angular speed ?1, which in turn causes the larger pulley to rotate. The loop does not slip on the pulleys. Det ermine the following in terms of II, RI, and ?1. i. The angular speed ?2 of the larger pulleyii. The angular momentum L2 of the larger pulley iii. The totai kinetic energy of the system2000E1. Lightbulbs A, B, and C are connected in the circuit shown above.a.List the bulbs in order of t heir brigh tn ess, from brightest to least bright・ If any bulbs have the same brightness,state which ones. Justify your answer.Now a switch S and a mH indue tor are added to the circuit; as shown above. The switch is closed at time t二0・b.Det ermine the curre nts IA, IB, and IC for the following times. i. Immediately after the switch is closedii. A long time after the switch is closedCopyright ? 2000 by College Entrance Examination Board. All rights reserved.College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registered trademarks of the College Entrance Examination Board.c.On the axes below, sketch the magnitude of the potential difference VL across the inductor as a function of time,from immediately after the switch is closed untila long time after the switch is closed.d.Now consider a similar circuit with an uncharged ?F capacitor instead of the induetor, as shown above. Theswitch is again closed at time t 二0・ On the axes below, sketch the magnitude of the potential difference Vcap across the capacitor as a function of time, from immediately after the switch is closed until a long time after the switch is closed.Copyright ? 2000 by College Entrance Examination Board. All rights reserved.College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registered trademarks of the College Entrance Examination Board.2000E2・Three particles, A, B, and C, have equal positive charges Q and are held in place at the vertices of anequilater&l triangle with sides of length 1, as shown in the figures below. The dot ted lines represe nt the bisec tors for each side. The base of the t riangle lies on the x-axis, and the altitude of the triangle lies on the y-axis.a.i.Point Pl, the intersection of the three bisec to rs, loca tes the geometric center of the triangle and is one pointwhere the electrie field is zero. On Figure 1 above, draw the elec trie field vec tors EA, EB, and EC at P, due to each of the three charges. Be sure your arrows are drawn to reflect the relative magnitude of the fields・ii.Another poi nt where the elec trie field is zero ispoint P2 at (0, y2). On Figure 2 above, draw electrie field vectors EA, EB, and EC at P2 due to each of the three point charges. Indicate below whether the magnitude of each of these vectors is greater than, less than, or the same as for point Pl.EA EB EC Greater than at Pl Less than at Pl The same as at Pl b. Explain why the x-component of the total electric field is zero at any point on the y-axis.c.Write a general expression for the electrie potential V at any point on the y-axis inside the trianglein terms of Q,1, and y.d.Describe how the answer to part (c) could be used to determine the y-coordinates of points Pl and P2 at whichthe electric field is zero. (You do not need toactually determine these coordinates.)Copyright ? 2000 by College Entrance Examination Board. All rights reserved.College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registered trademarks of the College Entrance Examination Board.2000E3. A capacitor consists of two conducting, coaxial, cylindrical shells of radius a and b, respec ti vely, and leng th L » b. The space bet ween the cylinders is filled with oil that has a dielectric constant K .Initially bothcylinders are uncharged, but then a battery is used to charge the capacitor, leaving a charge +Q on the inner cylinder and -Q on the outer cylinder, as shown above. Let r be the radial distance from the axis of the capacitor.ing Gauss，s 1aw, determine the electrie field midway along the length of the cylinder for the following valuesof r, in t erms of the given qua ntities and fundamental constants. Assume end effects are negligible. i.a b. Determine the following in terms of the givenquantities and fundamentai constants.i. The potential difference across the capacitor ii. The capacitance of this capacitorc.Now the capacitot is discharged and the oil is drained from it. As shown above, a battery of emf ? is connectedto opposite ends of the inner cylinder and a battery of emf 3? is connected to opposite ends of the outer cylinder. Each cylinder has resistance R. Assume that end effects and the contributions to the magnetic field from the wires are negligible. Using Ampere" s law, determine the magnitude Bof the magnetic field midway along the length of the cylinders due to the current in the cylinders for the following values of r. i. a Copyrigh t ? 2000 by College Ent rance Examina tion Board. All rights reserved.College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registered trademarks of the College Entrance Examination Board.AP? Physics C2000 Free response QuestionsThe mat erials included in these files are intended for use by AP teachers for course and exam preparation in the classroom; permission for any other use must be sought from the Advanced Placement Program?. Teachers may reproduce them, in whole or in part, in limited quantities, for face-to-face teaching purposes but may not mass distribute the materials,electronically or otherwise. These mat erials and any copies made of t hem may not be resold, and the copyright notices must be retained as they appear here. This permission does not apply to any third-party copyrights contained herein.These materials were produced by Educational Testing Service? (ETS?), which develops and administers the examinations of the Advanced Placement Program for the College Board. The College Board and Education&l Testing Service (ETS) are dedicated to the principle of equal opportunity, and theirprograms, services, and employment policies are guided by that principle.The College Board is a national nonprofit membership association dedicated to preparing, inspiring, and connecting students to college and opportunity. Founded in 1900, the association iscomposed of more than 4,200 schools, colleges, universities, and other educational organizations. Each year, the College Board serves over three million students and their parents，22,000 high schools, and 3, 500 colleges, through major programs and services in college admission, guidance, assessment, financial aid, enrollment, and teaching andlearning・ Among its best-known programs are the SAT?, the PSAT/NMSQT?, and the Advanced Placement Program? (AP?). The College Board is committed to the principles of equity andexcellence, and that commitment is embodied in all of its programs, services, activities, and concerns.API EL is a trademark owned by the College Ent rance Examination Board・PSAT/NMSQT is a registeted trademark jointly owned by the College Entrance Examination Board and the National Merit Scholarship Corporation. Educational Testing Service and ETS are registered trademarks of Educational Testing Service.Copyright ? 2000 by College Entrance Examination Board. All rights reserved.College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registered trademarks of the College Entrance Examination Board.(2000 Ml) You are conducting an experiment to measure the acceleration due to gravity gu at an unknown location. In the measurement apparatus, a simple pendulum swings past a photogate located at the pendulum^ s lowest point, which records the time tlO for the pendulum to undergo 10 fulloscillations. The pendulum consists of a sphere of mass m at the end of a st ring and has a length 1. There are four versions of this apparatus, each with a different length. All four are at the unknown location, and the data shown below are sent to you during the experiment.tio T T2 ? (s) (s) (s2) (cm) 12 18 21 32 a. For each pendulum, calculate the period T and the square of the period. Use a reasonable number of significant figures. Enter these results in the table above.b.On the axes below, plot the square of the period versus the length of the pendulum. Draw a best-fit straight linefor this data. c. Assuming that each pendulum undergoes small amplitude oscillations, from your fit determine the experimentai value gexp of the acceleration due to gravity at this unknown location. Justify your answer.d.If the measurement apparatus allows a determination of gexp that is accurate to within 4%, is your experimentalvalue in agreement with the value m/s2 ? Justify your answer.e.S omeone informs you that the experimental apparatus isin fact near Earth^ s surface, but that the experiment has been conducted inside an elevator with a constant acceleration a. Assuming that your experimentai value g is exact, determine the magnitude and direction of the elevatoH s acceleration.Copyright ? 2000 by College Entrance Examination Board. All rights reserved.College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registered trademarks of the College Entrance Examination Board.2000M2. A rubber ball of mass m is dropped from a cliff. As the ball falls, it is subject to air drag (a resistive force caused by the air). The drag force on the ball has magnitude bv2, where b is a const&nt drag coefficient and v is the instantaneous speed of the ball. The drag coefficient b is directly proportional to the cross-sectional area of the ball and the density of the air and does not depend on the mass of the ball. As the ball falls, its speed approaches a constant value called the terminal speed.a.On the figure below, draw and label all the forces on the ball at some inst&nt before it reaches terminal speed.b.State whether the magnitude of theacceleration of the ball of mass m increases, decreases, or remains the sameas the ball approaches terminal speed. Explain.c.Write, but do NOT solve, a differential equation for the instantaneous speed v of the ball in terms of time t, thegiven quantities, and fundamentai constants.d・Determine the terminal speed vt in terms ofthe given quantities and fundamental constants.e. Determine the energy dissipated by the drag force during the fall if the ball is released at height h and reachesits terminal speed before hitting the ground, in terms of the given quantities and fundamental constants.2000M3・ A pulley of radius R1 and rotational inertiaII is mounted on an axle with negligible friction. A light cord passing over the pulley has two blocks of mass m attached to either end, as shown above. Assume that the cord does not slip on the pulley.Determine the answers to parts (a) and (b) in terms of m, Rl, II, and fundamental constants. a. Determine the tension T in the cord.b.One block is now removed from the right and hung on the left・ When the system is released from rest, the threeblocks on the left accelerate downward with an accelera tion g/3 • Det ermine the followin g, i. The tension T3 in the section of cord supporting the three blocks on the left ii. The tension T1 in the section of cord supporting the single block on the right iii. The rotation&l inertia II of the pulleyCopyright ? 2000 by College Entrance Examination Board. All rights reserved.College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registered trademarks of the College Entrance Examination Board.c.The blocks are now removed and the cord is tied into a loop, which is passed around the original pulley and asecond pulley of radius 2R1 and rotational inertia 1611. The axis of the original pulley is attached to a motor that rotates it at angular speed ?1, which in turn causes the larger pulley to rotate. The loop does not slip on the pulleys.Det ermine the following in terms of II, RI, and ?1. i. The angular speed ?2 of the larger pulleyii. The angular momentum L2 of the larger pulley iii. The total kinetic energy of the system2000E1. Lightbulbs A, B, and C are connected in the circuit shown above.a.List the bulbs in order of t heir brigh tn ess, from brightest to least bright. If any bulbs have the same brightness,state which ones. Justify your answer.Now a switch S and a mH indue tor are added to the circuit; as shown above. The switch is closed at time t 二0.b.Det ermine the curre nts IA, IB, and IC for the following times. i. Immediately after the switch is closed ii. A long time after the switch is closedCopyright ? 2000 by College Entrance Examination Board. All rights reserved.College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registered trademarks of the College Entrance Examination Board.c.On the axes below, sketch the magnitude of thepotenti&l difference VL across the inductor as a function of time,from immediately after the switch is closed unt订a long time after the switch is closed.d.Now consider a similar circuit with an uncharged ?F capacitor instead of the inductor, as shown above. Theswitch is again closed at time t = 0. On the axes below, sketch the magnitude of the potential difference Vcap across the capacitor as a function of time, from immediately after the switch is closed until a long time after the switch is closed.Copyright ? 2000 by College Entrance Examination Board. All rights reserved.College Board, Advanced Placement Program, AP, SAT,and the acorn logo are registered trademarks of theCollege Entrance Examination Board.。
2018ap物理c力学大题
2018ap物理c力学大题
2018年AP物理C力学大题主要涉及以下几个方面：
1. 力学基本概念，题目可能涉及牛顿运动定律、摩擦力、弹簧力、重力等基本力学概念。
学生需要理解这些概念并能够运用它们
解决问题。
2. 动量和能量，题目可能涉及动量守恒定律、动能、势能、机
械能守恒等内容。
学生需要能够分析物体的动能和势能变化，并理
解动量守恒的应用。
3. 旋转运动，题目可能涉及刚体的平衡、转动惯量、角动量等
内容。
学生需要理解刚体平衡的条件，能够计算刚体的转动惯量并
应用相关知识解决问题。
4. 振动和波动，题目可能涉及弹簧振子、简谐振动、波速、波
长等内容。
学生需要理解振动的特点、波动的传播规律，并能够运
用相关公式解决问题。
总体来说，2018年AP物理C力学大题涵盖了力学的基本概念、
动量和能量、旋转运动、振动和波动等多个方面的内容。
学生在备考时需要扎实掌握这些知识点，并能够灵活运用到解决实际问题的能力。
希望这些信息能够对你有所帮助。
【AP物理C】【真题】解答题 C1973
AP® Physics C错误！未找到引用源。
1973 Free Response QuestionsThese materials were produced by Educational Testing Service® (ETS®), which develops and administers the examinations of the Advanced Placement Program for the College Board. The College Board and Educational Testing Service (ETS) are dedicated to the principle of equal opportunity, and their programs, services, and employment policies are guided by that principle.The College Board is a national nonprofit membership association dedicated to preparing, inspiring, and connecting students to college and opportunity. Founded in 1900, the association is composed of more than 4,200 schools, colleges, universities, and other educational organizations. Each year, the College Board serves over three million students and their parents, 22,000 high schools, and 3,500 colleges, through major programs and services in college admission, guidance, assessment, financial aid, enrollment, and teaching and learning. Among its best-known programs are the SAT®, thePSAT/NMSQT®, and the Advanced Placement Program® (AP®). The College Board is committed to the principles of equity andexcellence, and that commitment is embodied in all of its programs, services, activities, and concerns.APIEL is a trademark owned by the College Entrance Examination Board. PSAT/NMSQT is a registered trademark jointly owned by the College Entrance Examination Board and the National Merit Scholarship Corporation. Educational Testing Service and ETS are registered trademarks of Educational Testing Service.1973M1. A horizontal force F is applied to a small block of mass m1 to make it slide along the top of a larger block of mass m2 and length l. The coefficient of friction between the blocks is μ. The larger block slides without friction along a horizontal surface. The blocks start from rest with the small block at one end of the larger block, as shown.a. On the diagrams below draw all of the forces acting on each block. Identify each force.b. Find the acceleration of each block. a1 and a2, relative to the horizontal surface.c. In terms of 1, a1, and a2, find the time t needed for the small block to slide off the endof the larger block.d. Find an expression for the energy dissipated as heat because of the friction betweenthe two blocks.1973M2. A 30-gram bullet is fired with a speed of 500 meters per second into a wall.a. If the deceleration of the bullet is constant and it penetrates 12 centimeters into the wall, calculate theforce on the bullet while it is stopping.b. If the deceleration of the bullet is constant and it penetrates 12 centimeters into the wall, how muchtime is required for the bullet to stop?c. Suppose, instead, that the stopping force increases from zero as the bullet penetrates. Discuss themotion in comparison to the case for a constant deceleration.1973M3. A ball of mass m is attached by two strings to a vertical rod. as shown above. The entire system rotates at constant angular velocity ω about the axis of the rod.a. Assuming ω is large enough to keep both strings taut, find the force each string exerts onthe ball in terms of ω, m, g, R, and θ.b. Find the minimum angular velocity, ωmin for which the lower string barely remains taut.1973E1. The plates of an isolated parallel plate capacitor are pulled apart very slowly by a forceF. Each plate has charge q and area A. Assume that edge effects are negligible, i.e., thespacing x is much smaller than the plate dimensions.a. Determine the change in capacitance as x is increased by dxb. Determine the change of stored energy in the capacitor as x is increased by dxc. How is the force F related to the change in stored energy ? Determine F in terms of x, q,and A.1973E2. A surveyor attempts to use a compass below a power line carrying a steady currentof 103 amperes. The compass Is 6.0 meters directly below the wire.a. If the horizontal component of the Earth’s field is 0.10 gauss, could the power linedisturb the compass reading? Give a quantitative argument.b. Suppose, instead, the current were 103 amperes of 60 cycles per second alternatingcurrent. Would the compass reading be disturbed? Explain your answerqualitatively in terms of the properties of the compass.1973E3. In a uniform magnetic field B directed vertically downward. a metal bar of mass m is released from rest and slides without friction down a track inclined at an angle , as shown above.The electrical resistance of the bar between its two points of contact with the track is R: the trackhas negligible resistance. The width of the track is l.a. Show on the diagram the direction of the current in the sliding bar.b. Denoting by v the instantaneous speed with which the bar is sliding down the incline,determine an expression for the magnitude of the current in the bar.c. Determine an expression for the force exerted on the bar by the magnetic field.学习使人进步d. Determine an expression for the terminal velocity of the sliding bar.。
2017ap物理c力学真题答案
2017ap物理c力学真题答案一、单项选择题【答案】a考点：电磁感应现象与电流的磁效应现象分辨a.我国水资源是有限的，所以水能是不可再生能源b.发光二极管主要就是由超导材料制成的c.试电笔在使用时，试电笔上的任何金属都不要接触，否则会有触电危险d.工业上采用超音波探伤仪能够检查出来金属零件内部的裂纹【答案】 d【解析】我国水资源是有限的，但水能是可再生能源，a选项不正确;发光二极管是由半导体材料制成的，b选项不正确;使用试电笔时不能接触笔尖金属体，必须接触笔尾金属体，这样才能形成通路，c选项不正确;故d选项正确，选填d考点：再生能源辨识;发光二极管材料;试电笔的采用;超声波应用领域。
a.使用红外线传输数字信号b.使用超声波传输数字信号c.采用光纤传输数字信号d.采用电磁波传输数字信号【答案】d一、单项选择题a.电路中的电阻变大，灯泡变亮b.电路中的电阻变大，灯泡变暗c.电路中的电阻变大，灯泡变暗d.电路中的电阻变大，灯泡变暗【答案】c【考点定位】滑动变阻器【答案】a【解析】电流表的正确使用方法是：与被测用电器串联;电流必须从电流表的正极流入，负极流出;所测量的电流不能超过电流表的量程;绝对不允许不经过用电器把电流表直接接在电源两极上;电压表的正确使用方法是：把它并联在用电器两端;必须让电流从正接线柱流入，从负接线柱流出(正接线柱与正极相连，负接线柱与负极相连);被测电压不能超过电压表所选的量程，否则会烧坏电压表. a、此图中是电流表，即串联在电路中，且正负接线柱是正确的，故a正确;b、此图中是电流表，相当于导线，所以此时将电流表并联，会发生短路，故b错误;c、此图中是电压表，应该并联在用电器两端，故c错误;d、此图中的电压表虽然并联在用电器两端，但正负接线柱接反了，故d错误;故选a.【考点定位】电流表的采用;电压表的采用a.电流表接电源b.电压表接电源c.导线接电源d.家用电器接电源【答案】b【考点定位】电路的连接a.l1、l2两端实际电压相同b.l1、l2电阻之比是25:38c.l1、l2的电流之比为25 :38d.通过调节电源电压，能使l1、l2同时正常工作【答案】b【解析】【考点定位】并联电路的特点a.电流表与的示数的比值将减小b.电压表的示数与电流表的示数的比值将增大c.电压表的示数与电流表示数的乘积将增大d.电流表与的示数的比值将减小【答案】a【解析】由电路图知道r1与r2并联，a测量干路部分的电流，当滑动变阻器的滑片p向右移动时，r1接入电路的电阻增加，电路总电阻增加，所以a与a2的示数减小，v与a1的示数不变。
洋桃课堂【AP物理C】【真题】解答题C2005
AP® Physics C2005 Free response QuestionsThese materials were produced by Educational Testing Service® (ETS®), which develops and administers the examinations of the Advanced Placement Program for the College Board. The College Board and Educational Testing Service (ETS) are dedicated to the principle of equal opportunity, and theirprograms, services, and employment policies are guided by that principle.The College Board is a national nonprofit membership association dedicated to preparing, inspiring, and connecting students to college and opportunity.Founded in 1900, the association is composed of more than 4,200 schools, colleges, universities, and other educational organizations. Each year, theCollege Board serves over three million students and their parents, 22,000 high schools, and 3,500 colleges, through major programs and services incollege admission, guidance, assessment, financial aid, enrollment, and teaching and learning. Among its best-known programs are the SAT®, the PSAT/NMSQT®, and the Advanced Placement Program® (AP®). The College Board is committed to the principles of equity andexcellence, and that commitment is embodied in all of its programs, services, activities, and concerns.Copyright © 2005 by College Entrance Examination Board. All rights reserved. College Board, Advanced Placement Program, AP, SAT, and the acorn logo are registered trademarks of the College Entrance Examination Board. APIEL is a trademark owned by the College Entrance Examination Board. PSAT/NMSQT is a registered trademark jointly owned by the College Entrance Examination Board and the National Merit Scholarship Corporation.Educational Testing Service and ETS are registered trademarks of Educational Testing Service.2005M1. A ball of mass M is thrown vertically upward with an initial speed of v o. It experiences a force of air resistance given by F = -kv, where k is a positive constant. The positive direction for all vector quantities is upward. Express all algebraic answers in terms of M, k, v o, and fundamental constants.a. Does the magnitude of the acceleration of the ball increase, decrease, or remain the same as the ball movesupward?increases decreases remains the sameJustify your answer.b. Write, but do NOT solve, a differential equation for the instantaneous speed v of the ball in terms of time t as theball moves upward.c. Determine the terminal speed of the ball as it moves downward.d. Does it take longer for the ball to rise to its maximum height or to fall from its maximum height back to theheight from which it was thrown?longer to rise longer to fallJustify your answer.e. On the axes below, sketch a graph of velocity versus time for the upward and downward parts of the ball's flight,where t f is the time at which the ball returns to the height from which it was thrown.2005M2. A student is given the set of orbital data for some of the moons of Saturn shown below and is asked to use the data to determine the mass M S of Saturn. Assume the orbits of these moons are circular.a. Write an algebraic expression for the gravitational force between Saturn and one of its moons.b. Use your expression from part (a) and the assumption of circular orbits to derive an equation for the orbitalperiod T of a moon as a function of its orbital radius R.c. Which quantities should be graphed to yield a straight line whose slope could be used to determine Saturn'smass?d. Complete the data table by calculating the two quantities to be graphed. Label the top of each column, includingunits.e. Plot the graph on the axes below. Label the axes with the variables used and appropriate numbers to indicate thescale.f. Using the graph, calculate a value for the mass of Saturn.2005M3. A system consists of a ball of mass M 2 and a uniform rod of mass M 1 and length d. The rod is attached toa horizontal frictionless table by a pivot at point P and initially rotates at an angular speed ω, as shown above left. The rotational inertia of the rod about point P is 31 M 1d2 . The rod strikes the ball, which is initially at rest. As a result of this collision, the rod is stopped and the ball moves in the direction shown above right. Express all answers in terms of M 1, M 2, ω, d, and fundamental constants.a. Derive an expression for the angular momentum of the rod about point P before the collision.b. Derive an expression for the speed v of the ball after the collision.c. Assuming that this collision is elastic, calculate the numerical value of the ratio M 1 / M 2d. A new ball with the same mass M 1 as the rod is now placed a distance x from the pivot, as shown above. Againassuming the collision is elastic, for what value of x will the rod stop moving after hitting the ball?2005E1. Consider the electric field diagram above.a. Points A, B, and C are all located at y = 0.06 m .i. At which of these three points is the magnitude of the electric field the greatest? Justify your answer.ii. At which of these three points is the electric potential the greatest? Justify your answer.b. An electron is released from rest at point B.i. Qualitatively describe the electron's motion in terms of direction, speed, and acceleration.ii. Calculate the electron's speed after it has moved through a potential difference of 10 V.c. Points B and C are separated by a potential difference of 20 V. Estimate the magnitude of the electric fieldmidway between them and state any assumptions that you make.d. On the diagram, draw an equipotential line that passes through point D and intersects at least three electric fieldlines.2005E2. In the circuit shown above, resistors 1 and 2 of resistance R1 and R2 , respectively, and an inductor of inductance L are connected to a battery of emf ε and a switch S. The switch is closed at time t = 0. Express all algebraic answers in terms of the given quantities and fundamental constants.a. Determine the current through resistor 1 immediately after the switch is closed.b. Determine the magnitude of the initial rate of change of current, dI/dt , in the inductor.c. Determine the current through the battery a long time after the switch has been closed.d. On the axes below, sketch a graph of the current through the battery as a function of time.Some time after steady-state has been reached, the switch is opened.e. Determine the voltage across resistor 2 just after the switch has been opened.2005E3. A student performs an experiment to obtain the value of μ0, the magnetic permeability of vacuum. Shemeasures the magnetic field along the axis of the long, 100-turn solenoid PQ shown above. She connects ends P and Q of the solenoid to a variable power supply and an ammeter as shown. End P of the solenoid is taped at the 0 cm mark of a meterstick. The solenoid can be stretched so that the position of end Q can be varied. The student then positions a Hall probe* in the center of the solenoid to measure the magnetic field along its axis. She measures the field for a fixed current of 3.0 A and various positions of the end Q. The data she obtains are shown below.a. Complete the last column of the table above by calculating the number of turns per meter.* A Hall Probe is a device used to measure the magnetic field at a point.b. On the axes below, plot the measured magnetic field B versus n . Draw a best-fit straight line for the data points.c. From the graph, obtain the value of μ0, the magnetic permeability of vacuum.d. Using the theoretical value of μ0 = 4π x 10-7 TM/A, determine the percent error in the experimental value of μ0computed in part (c).。
大学物理物理c答案
大学物理答案及评分标准（C 卷）一、填空题：1、2m/s -6m/s2、是：保守力做功跟路径无关。
3、ωJ 和221ωJ 4、导体内场强处处为零 5、取向极化和位移极化 6、304r r l Id B d ⨯⋅=μπ 7、M RT 2和M RT 38、R 25和R 23 9、开尔文表述是：不可能从单一的热源吸收热量使之完全变成有用功而不引起其他的变化。
10、频率相同、振动方向相同、位相差恒定。
二、选择题：1、（B ）2、（D ）3、（B ）4、（A ）5（A ）三、判断题：１．（×） ２.（×） 3. （×） 4. （×） 5. （×） 6. （√） 7. （×） 8. （×） 9. （×）10. （√）四、解答题：1. 解：（1）根据题意：Kv a -=， 所以Kv dt dv -=，分离变量后，Kdt vdv -=，.................................(1分) 积分得，⎰⎰-=t v v Kdt v dv 00，所以有Kt e v t v -=0)(；....................... (3分) 同理，可以求得)1(00Kt e K v x x ---=。
......................................... (1分) （2）根据题意，Kx a =所以， dx Kx dx dtdv ⋅=⋅，积分得⎰⎰=x x v v Kxdx vdv 00；............. (1分) 所以有：)(202202x x K v v -+=.............................................(4分)2. 解：设导体平板的面积为S ， 各面的电荷面密度分别为1σ、 2σ、3σ、4σ，根据电荷守恒的条件：A Q S S =+21σσ (1)B Q S S =+43σσ（2）---------------------------- （2分）在金属板内取如图所示的高斯面，根据高斯定理有：032=+σσ （3）---------------------------- (3分)根据场强叠加原理，金属板内某点P 的场强为零：40302012222εσεσεσεσ-+=p E -----------------（3分） 联立求解得：SQ Q B A 241+==σσ SQ Q B A 232-=-=σσ----------------------（2分） 3. 解：由于同轴电缆导体内的电流均匀分布，其磁场轴对称分布。
ap物理c答案
ap物理c答案【篇一：ap物理c】ass=txt>牛顿力学、占整个physics c力学考试的100%其中：a.kinematics ：运动学占18%包括：矢量（ vectors）的概念：既有大小，又有方向；矢量代数（ vector algebra）：矢量和的三角形法则是必须熟练掌握的，最简单的记忆方法就是花萌萌面对两段直的折线路径（对应两段位移矢量之和），她会选择直接连接出发点和终点的直线捷径（等效的对应两个位移矢量和），这样构成了一个矢量和三角形。
矢量的加减，点乘和叉乘，是矢量分析的基础，是我们学习ap物理c的基本数学框架一定要熟练掌握。
矢量在直角坐标系中的分量（components of vectors,coordinate systems）,特别强调的是物理上只会用“右手系”，也就是从x轴到y轴的右手螺旋拇指指向z轴，这个和叉乘的定义是一样的，好记！有了ta，大家在学电磁学的时候就不用左右手的拧麻花了。
ap 物理c还需要掌握柱坐标和球坐标，这在需要柱对称和球对称的积分问题时，就很有用了。
运动学中要用到的三大矢量：位移、速度和加速度（displacement, velocity and acceleration)，特别要注意别把距离（或者叫路程distance），速率（speed）和前面的概念搞混了，后两个概念是标量，只有在一些特殊情况下才和对应矢量的模（大小）相等。
一维运动（motion in one dimension）：一维运动的矢量性就记住有正负的方向就行，对于一维匀加速直线运动，务必掌握其最重要的三个方程：第一求速度的公式，角标i（initial）和f（final）总是代表初和末，这个公式只要从匀加速度等于平均加速度的定义就可以得到：第二个求位移的公式：，这个公式可以理解为保持初速度的匀速运动位移和初速为零的匀加速运动位移之和（第二项在v-t图中是一个三角形面积，底为⊿t，高为a*⊿t）第三个公式是把前面两个公式消去变量⊿t，得：更方便的记忆方法是公式左边用牛顿第二定律f=ma，变成外力做功的形式：f⊿x, 左边多出来的2/m转到右边，右边就正好得到物体动能的变化。
2004AP_物理C电磁真题选择题
2004AP_物理C电磁真题选择题36. Three 1/2 µF capacitors are connected in seriesas shown in the diagram above. Thecapacitance of the combination is (A) 0.1 µF(B) 1 µF (C) 2/3 µF (D) ? µF (E) 1/6µF37. A hair dryer is rated as 1200 W, 120 V.Its effective internal resistance is(A) 0.1 Ω (B)10 Ω (C) 12Ω(D) 120 Ω (E)1440 Ω38. A point charge +Q is inside an unchargedconducting spherical shell that in turn is nearseveral isolated point charges, as shown above.The electric field at point P inside the shelldepends on the magnitude of(A) Q only(B) the charge distribution on the sphere only(C) Q and the charge distribution on the sphere(D) all of the point charges(E) all of the point charges and the charge distribution on the sphere39. In a certain region, the electric field alongthe x-axis is given byE = ax + b, where a = 40 V/m2and b = 4 V/m.The potential difference between the originand x = 0.5 m is(A) -36 V (B) -7 V (C) -3 V (D) 10 V(E) 16 VQuestions 40-41A particle of charge +e and mass m moves with speed v perpendicular to a uniform magnetic fieldB directed into the page. The path of the particle isa circle of radius r, as shown above.40. Which of the following correctly gives the direction of motion and the equationrelating v and r ?Dir ection Equation(A) Clockwise eBr = mv(B) Clockwise eBr = mv2(C) Counterclockwise eBr = mv(D) Counterclockwise eBr = mv2(E) Counterclockwise eBr2 = mv241. The period of revolution of the particleis(A) mr/eB (B)(C) 2πm/eB (D) 2(E)242. A 20 µF parallel-plate capacitor is fully charged to 30V. The energy stored in the capacitor is most nearly(A) 9 x 103 J (B) 9 x 10-3 J (C) 6 x 10-4 J(D) 2 x 10-4 J (E) 2 x 10-7 J43. A potential difference V is maintained betweentwo large, parallel conducting plates. Anelectron starts from rest on the surface of oneplate and accelerates toward the other. Itsspeed as it reaches the second plate isproportional to(A) 1/V(B)V1(C) V(D) V(E) V244. A wire of radius R has a current I uniformlydistributed across its cross-sectional area. Ampere's law is used with a concentric circular path of radius r, with r < R, to calculate the magnitude of the magnetic field B at a distance r from the center of the wire. Which of the following equationsresults from a correct application of Ampere's law to this situation?(A) B(2πr) = µ0I (B) B(2πr) = µ0I(r 2/R 2) (C) B(2πr) = 0 (D) B(2πR) = µ0I (E) B(2πR) = µ0I(r 2/R 2)Questions 45-46Particles of charge Q and -4Q are located on the x-axis as shown in the figure above. Assume the particles are isolated from all other charges.45. Which of the following describes the directionof the electric field at point P ? (A) +x (B) +y (C)-y(D) Components in both the -x- and +y-directions(E) Components in both the +x- and -y-directions46. At which of the labeled points on the x-axis is the electric field zero? (A) A (B) B (C) C (D) D (E) E47. When the switch S is open in the circuitshown above, the reading on the ammeter A is 2.0 A. When the switch is closed, the reading on the ammeter is (A) doubled (B) increased slightly but not doubled (C) the same(D) decreased slightly but not halved (E) halved48. Two conducting cylindrical wires are made outof the same material. Wire X has twice the length and twice the diameter of wire Y. What is the ratio R x /R y of their resistances?(A) 1/4 (B) ? (C) 1 (D) 2 (E) 449. A solid metallic sphere of radius R has chargeQ uniformly distributed on its outer surface. A graph of electric potential V as a function of position r is shown above. Which of thefollowing graphs best represents the magnitude of the electric field E as a function of position rfor this sphere?50. Two parallel wires, each carrying a current I, repel each other with a force F. If bothcurrents are doubled, the force of repulsion is(A) 2F (B) 22 F (C) 4F (D) 24 F (E) 8F51. A circular current-carrying loop lies so that the plane of the loop is perpendicular to a constant magnetic field of strength B . Suppose that the radius R of the loop could be made to increase with time t so that R = at, where a is a constant. What is the magnitude of the emf that would begenerated around the loop as a function of t ? (A) 2πBa 2t (B)2πBat(C)2πBt(D)πBa 2t (E) (π/3)Ba 2t 352. The figures above show parts of two circuits,each containing a battery of emf ε and internalresistance r. The current in each battery is 1 A, but the direction of the current in one battery is opposite to that in the other. If the potential differences across the batteries' terminals are 10 V and 20 V as shown, what are the values of ε and r ? (A) ε = 5 V, r = 15 Ω (B) ε =IOV, r=100 Ω (C) ε = 15 V, r = 5 Ω(D) ε = 20 V, r = 10 Ω(E) The values cannot be computed unless the complete circuits are shown.53. A charged particle can move with constant velocity through a region containing both an electric field and a magnetic field only if the(A) electric field is parallel to the magneticfield(B) electric field is perpendicular to the magnetic field(C) electric field is parallel to the velocity vector(D) magnetic field is parallel to the velocity vector(E) magnetic field is perpendicular to the velocity vector54. A conducting loop of wire that is initiallyaround a magnet is pulled away from the magnet to the right, as indicated in the figure above, inducing a current in the loop. What is the direction of the force on the magnet and the direction of the magnetic field at the center of the loop due to the induced current? Direction of Magnetic Field at Direction of Center of Loop due Force on the Magnet to Induced Current (A) To the right To the right (B) To the right To the left (C) To the left To the right (D) To the left To the left (E) No direction; To the left the force is zero.55. A square loop of wire carrying a current I isinitially in the plane of the page and is located in a uniform magnetic field B that pointstoward the bottom of the page, as shown above. Which of the following shows the correct initial rotation of the loop due to the force exerted on it by the magnetic field?56. In the circuit shown above, the equivalentresistance of the three resistors is (A) 10.5 Ω (B) 15Ω (C) 20 Ω (D) 50 Ω (E) 115 ΩQuestions 57-58As shown in the figure above, six particles, each with charge +Q , are held fixed and ate equally spaced around the circumference of a circle of radius R .57. What is the magnitude of the resultantelectric field at the center of the circle?(C)0 (E)2032QR πε58. With the six particles held fixed, how muchwork would be required to bring a seventh particle of charge + Q from very far away and place it at the center of the circle?(A) 00 (C) 22032Q R πε(D) 2032Q R πε (E) 209Q R πεQuestions 59-61The diagram above shows equipotential lines produced by an unknown charge distribution. A, B, C, D, and E are points in the plane.59. Which vector below best describes the directionof the electric field at point A ?(E) None of these; the field is zero.60. At which point does the electric field havethe greatest magnitude? (A) A(B) B (C) C (D) D (E) E61. How much net work must be done by anexternal force to move a -1 µC point charge from rest at point C to rest at point E ? (A) -20 µJ (B) -10 µJ (C) 10 µJ (D) 20 µJ(E) 30 µJ62. One of Maxwell's equations can be writtenasdE dsdtφ=-. This equation expressesthe fact that(A) a changing magnetic field producesan electric field(B) a changing electric field produces amagnetic field(C) the net magnetic flux through aclosed surface depends on thecurrent inside(D) the net electric flux through a closedsurface depends on the charge inside(E) electric charge is conserved63. The plates of a parallel-plate capacitor of crosssectional area A are separated by a distance d,as shown above. Between the plates is adielectric material of constant K. The plates areconnected in series with a variable resistance Rand a power supply of potential difference V.The capacitance C of this capacitor willincrease if which of the following is decreased?(A) A (B) R (C) K(D) d (E) V64. The currents in three parallel wires, X, Y, and Z,each have magnitude l and are in the directionsshown above. Wire Y is closer to wire X than towire Z. The magnetic force on wire Y is(A) zero (B) into the page (C) out of the page(D) toward the bottom of the page(E) toward the left 65. A physics problem starts: "A solid sphere has charge distributed uniformly throughout. . . "It may be correctly concluded that the(A) electric field is zero everywhere inside thesphere(B) electric field inside the sphere is the sameas the electric field outside(C) electric potential on the surface of thesphere is not constant(D) electric potential in the center of the sphereis zero(E) sphere is not made of metalQuestions 66-67 relate to the circuit represented below. The switch S, after being open for a long time, is then closed.66. What is the current in the circuit after theswitch has been closed a long time?(A) 0 A(B) 1.2 A(C) 2 A(D) 3 A(E) 12 A67. What is the potential difference across theresistor immediately after the switch is closed?(A) 0 V(B) 2 V(C) 7.2 V(D) 8 V(E) 12 V68. A uniform spherical charge distribution hasradius R.. Which of the following is true of the electric field strength due to this chargedistribution at a distance r from the center ofthe charge?(A) It is greatest when r = 0.(B) It is greatest when r = R/2.(C) It is directly proportional to r when r >R.(D) It is directly proportional to r when r <R.(E) It is directly proportional to r2.4 H69. When a negatively charged rod is brought near,but does not touch, the initially unchargedelectroscope shown above, the leaves springapart (I). When the electroscope is thentouched with a finger, the leaves collapse (II).When next the finger and finally the rod areremoved, the leaves spring apart a second time (III). The charge on the leaves is(A) positive in both I and III(B) negative in both I and III(C) positive in I, negative in III(D) negative in I, positive in III(E) impossible to determine in either I or III70. A sheet of copper in the plane of the page isconnected to a battery as shown above,causing electrons to drift through the coppertoward the bottom of the page. The coppersheet is in a magnetic field B directed into the page. P1 and P2are points at the edges of the strip. Which of the following statementsis true?(A) P1 is at a higher potential than P2.(B) P2 is at a higher potential than P1.(C) P1 and P2 are at equal positive potential.(D) P1 and P2 are at equal negative potential.(E) Current will cease to flow in the copper sheet.。
大学物理c的试题及答案
大学物理c的试题及答案一、选择题（每题2分，共20分）1. 下列哪个选项是牛顿第一定律的描述？A. 物体在没有外力作用下，总保持静止或匀速直线运动状态B. 物体的加速度与作用力成正比，与质量成反比C. 物体的加速度与作用力成正比，与质量成正比D. 物体在任何情况下都保持静止或匀速直线运动状态答案：A2. 光在真空中的传播速度是多少？A. 299,792,458 m/sB. 299,792,458 km/sC. 299,792,458 km/hD. 299,792,458 m/h答案：A3. 以下哪个是电场强度的定义？A. 电场力与电荷的比值B. 电荷与电场力的比值C. 电场力与电场强度的比值D. 电场强度与电荷的比值答案：A4. 根据热力学第一定律，系统内能的增加等于系统吸收的热量与对外做的功之和。
A. 正确B. 错误答案：A5. 电磁波的频率与波长的关系是？A. 频率与波长成正比B. 频率与波长成反比C. 频率与波长无关D. 频率与波长成正比，但只在特定条件下成立答案：B6. 根据麦克斯韦方程组，变化的磁场会产生什么？A. 变化的电场B. 恒定的电场C. 恒定的磁场D. 没有影响答案：A7. 欧姆定律描述的是电流、电压和电阻之间的关系，其表达式为？A. I = V/RB. I = R/VC. V = I * RD. R = V/I答案：A8. 以下哪个选项是描述波的干涉现象？A. 两个波相遇时，振幅相加B. 两个波相遇时，振幅相减C. 两个波相遇时，振幅不变D. 两个波相遇时，振幅消失答案：A9. 根据量子力学，电子在原子中的运动状态是由什么决定的？A. 电子的电荷B. 电子的质量C. 电子的能级D. 电子的动量答案：C10. 根据相对论，当物体的速度接近光速时，其质量会如何变化？A. 质量不变B. 质量增加C. 质量减少D. 质量消失答案：B二、填空题（每题2分，共20分）1. 根据牛顿第二定律，物体的加速度与作用力成_______，与物体的质量成_______。
【AP物理C】【真题】解答题2008力学
AP® Physic s C: Mechan ics2008 Free-Respon se Questi onsThe Colleg e Board: Connec tingStuden ts to Colleg e Succes sThe Colleg e Boardis a not-for-profit member shipassoci ation whosemissio n is to connec t studen ts to colleg e succes s andopport unity. Founde d in 1900, the associ ation is compos ed of more than 5,000 school s, colleg es, univer sitie s, and othereducat ional organi zatio ns. Each year, the Colleg e Boardserves sevenmillio n studen ts and theirparent s, 23,000 high school s, and 3,500 colleg es throug h majorprogra ms and servic es in colleg e admiss ions, guidan ce, assess ment, financ ial aid, enroll ment, and teachi ng andlearni ng. Amongits best-knownprogra ms are the SAT®, the PSAT/NMSQT®, and the Advanc ed Placem ent Progra m® (AP®). The Colleg e Boardis commit ted to the princi plesof excell enceand equity, and that commit mentis embodi ed in all of its progra ms, servic es, activi ties, and concer ns.© 2008 The Colleg e Board. All rights reserv ed. Colleg e Board, Advanc ed Placem ent Progra m, AP, AP Centra l, SAT, and the acornlogo are regist eredtradem arksof the Colleg e Board. PSAT/NMSQTis a regist eredtradem ark of the Colleg e Boardand Nation al MeritSchola rship Corpor ation.Permis sionto use copyri ghted Colleg e Boardmateri als may be reques ted online at:www.colleg eboar /inquir y/cbperm it.html.Visitthe Colleg e Boardon the Web: www.colleg eboar .AP Centra l is the offici al online home for the AP Progra m: apcent ral.colleg eboar .PHYSI C S C: MECHA N ICSSECTI O N IITime -45 minut e s3 Quest i onsDirec t ions : Answe r all three quest i ons. The sugge s ted time is about 15 minut e s for answe r ing each of the quest i ons, which are worth 15 point s each. The parts withi n a quest i on may not have equal weigh t . Show all your work in the pink bookl e t in the space s provi d ed after each part , NOT in this green inser t.2008M 1. A skier of mass M is skiin g down a frict i onle s s hill that makes an angle θ with the horiz o ntal , as shown in the diagr a m. The skier start s from rest at time t = 0 and is subje c t to a veloc i ty-depen d ent drag force du e to air resis t ance of the form F = –bv, where v is the veloc i ty of the skier and b is a posit i ve const a nt. Expre s s all algeb r aic answe r s in terms of M, b, θ, and funda m enta l const a nts.(a) On the dot below that repre s ents the skier , draw a free -body diagr a m indic a ting and label i ng all of the force s that act on the skier while the skier desce n ds the hill.(b) Write a diffe r enti a l equat i on that can be used to solve for the veloc i ty of the skier as a funct i on oftime.(c) Deter m ine an expre s sion for the termi n al veloc i ty v T of the skier .(d) Solve the diffe r enti a l equat i on in part (b) to deter m ine the veloc i ty of the skier as a funct i on of time, showi n g all your steps .(e) On the axes below , sketc h a graph of the accel e rati o n a of the skier as a funct i on of time t, and indic a te the initi a l value of a. Take downh i ll as posit i ve.taO2008M2. The horizo ntalunifor m rod shownabovehas length 0.60 m and mass 2.0 kg. The left end of the rod is attach ed to a vertic al suppor t by a fricti onles s hingethat allows the rod to swingup or down. The rightend of th e rod is suppor ted by a cord that makesan angleof 30° with the rod. A spring scaleof neglig iblemass measur es the tensio n in the cord. A 0.50 kg blockis also attach ed to the rightend of the rod.(a) On the diagra m below, draw and labelvector s to repres ent all the forces acting on the rod. Show each forcevector origin ating at its pointof applic ation.(b)Calcul ate the readin g on the spring scale.The rotati onalinerti a of a rod aboutits center is 1ML2, whereM is the mass of the rod and L is its length.12Calcul ate the rotati onalinerti a of the rod-blocksystem aboutthe hinge.(d)If the cord that suppor ts the rod is cut near the end of the rod, calcul ate the initia l angula r accele ratio n of th erod-blocksystem aboutthe hinge.2008M3. In an experi mentto determ ine the spring consta n t of an elasti c cord of length 0.60 m, a studen t hangsthe cord from a rod as repres ented aboveand then attach es a variet y of weight s to the cord. For each weight, the studen t allows the weight to hang in equili brium and then measur es the entire length of the cord. The data are record ed in the tablebelow:(a)Use the data to plot a graphof weight versus length on the axes below. Sketch a best-fit straig ht line throug hthe data.(b) Use the best-fit line you sketch ed in part (a) to determ ine an experi menta l valuefor the spring consta nt k ofthe cord.The studen t now attach es an object of unknow n mass m to the cord and holdsthe object adjace nt to the pointat whichthe top of the cord is tied to the rod, as repres ented above. When the object is releas ed from rest, it falls1.5 m before stoppi ng and turnin g around. Assume that air resist anceis neglig ible.(c)Calcul ate the valueof the unknow n mass m of the object.(d)i. Calcul ate how far down the object has fallen at the moment it attain s its maximu m speed.ii.Explai n why this is the pointat whichthe object has its maximu m speed.iii.Calcul ate the maximu m speedof the object.。
ap物理c力学试卷
选择题一个物体在水平面上做匀速直线运动，若突然撤去所有外力，物体将如何运动？A. 继续做匀速直线运动（正确答案）B. 逐渐减速至停止C. 开始做匀加速直线运动D. 做曲线运动下列哪个力是弹力？A. 重力B. 摩擦力C. 电磁力D. 弹簧的拉力（正确答案）一个物体在竖直上抛运动中，到达最高点时，它的速度为零，此时它的加速度是？A. 零B. 9.8 m/s²（正确答案）C. -9.8 m/s²D. 无法确定关于牛顿第三定律，下列说法正确的是？A. 作用力和反作用力大小相等，方向相同B. 作用力和反作用力作用在不同物体上（正确答案）C. 作用力和反作用力可以相互抵消D. 作用力先于反作用力产生一个物体在恒力作用下做匀加速直线运动，如果突然将力的大小减半，但方向不变，物体的运动状态将如何变化？A. 继续做匀加速直线运动，但加速度减小（正确答案）B. 开始做匀速直线运动C. 开始做匀减速直线运动D. 做曲线运动下列哪个选项描述了动量守恒定律的适用条件？A. 系统不受外力作用或所受合外力为零（正确答案）B. 系统内各物体速度必须相同C. 系统内各物体加速度必须相同D. 系统内各物体质量必须相等一个物体在光滑的水平面上受到一个水平恒力的作用，它将做何种运动？A. 匀速直线运动B. 匀加速直线运动（正确答案）C. 匀减速直线运动D. 曲线运动关于冲量，下列说法正确的是？A. 冲量是矢量，方向与力的方向相同（正确答案）B. 冲量是标量，只有大小没有方向C. 冲量的大小等于力与时间的乘积，方向与速度方向相同D. 冲量的大小等于力与位移的乘积一个物体在竖直方向上受到重力和空气阻力的作用，下落过程中它的加速度将如何变化？A. 保持不变B. 逐渐增大C. 逐渐减小（正确答案，假设空气阻力随速度增大而增大）D. 先增大后减小。