AP物理C真题2010

AP® Physics C: Mechanics

2010 Free-Response Questions

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TABLE OF INFORMATION FOR 2010 and 2011

meter, m mole, mol watt, W farad, F kilogram, kg hertz, Hz coulomb, C tesla, T

second, s newton, N volt, V degree Celsius, C ∞

ampere, A pascal, Pa ohm, W

electron-volt, eV UNIT

SYMBOLS

kelvin, K joule, J henry, H

PREFIXES

Factor Prefix Symbol 910

giga G 610 mega M 310 kilo k

210- centi c 310- milli m 610- micro m

910- nano n

1210-

pico p

The following conventions are used in this exam.

I. Unless otherwise stated, the frame of reference of any problem is

assumed to be inertial. II. The direction of any electric current is the direction of flow of positive

charge (conventional current).

III. For any isolated electric charge, the electric potential is defined as zero at

an infinite distance from the charge.

ADVANCED PLACEMENT PHYSICS C EQUATIONS FOR 2010 and 2011

PHYSICS C: MECHANICS

SECTION II Time—45 minutes

3 Questions

Directions: Answer all three questions. The suggested time is about 15 minutes for answering each of the questions, which are worth 15 points each. The parts within a question may not have equal weight. Show all your work in the pink booklet in the spaces provided after each part, NOT in this green insert.

Mech. 1.

Students are to conduct an experiment to investigate the relationship between the terminal speed of a stack of

falling paper coffee filters and its mass. Their procedure involves stacking a number of coffee filters, like the one shown in the figure above, and dropping the stack from rest. The students change the number of filters in the stack to vary the mass m while keeping the shape of the stack the same. As a stack of coffee filters falls, there is an air resistance (drag) force acting on the filters.

(a) The students suspect that the drag force D F is proportional to the square of the speed u : 2D F C u =, where C is a constant. Using this relationship, derive an expression relating the terminal speed T u to the mass m .

The students conduct the experiment and obtain the following data.

(i) Assuming the functional relationship for the drag force above, use the grid below to plot a linear graph

as a function of m to verify the relationship. Use the empty boxes in the data table, as appropriate, to record any calculated values you are graphing. Label the vertical axis as appropriate, and place numbers on both axes.