大学物理双语2012-2013-1月A答案及评分标准

标准答案及评分标准
一．Choice(20分，每题4分)
1. a
2. b
3. c
4. d
5. a
二．Blanks （20分）
6. 0.5 （1分） 3 (1分) 1/2 (1分)
π/6（2分） 3π or 9.42 (3pts)
7. 1.26 （3分）
8. 2.26°(3分)
9. 3.56×10-28 (3分)
10. 1.14eV (3分)
三．Questions(10分)
11. (5pts)
The relativity principle: The laws of physics must be the same in all inertial reference frames. 一切物理规律在惯性系中相同。

(2分)
The constancy of the speed of light: The speed of light in vacuum has the same value c in all inertial frames, regardless of the velocity of the observer or the velocity of the source emitting the light. 真空中的光速在任何惯性系中都是c ，与光源或观察者的运动无关。

（3分）
12. (5pts)
The maximum kinetic energy of photoelectrons is independent of light intensity. (2分)
No electrons are emitted if the incident light frequency falls below some cutoff frequency fc , whose value is characteristic of the material being illuminated, regardless of the light intensity.（3分）
四. Problems （50分）
13(10pts) (1) The average transitional kinetic energy 21101.623-⨯==
kT K t J ………………… 3pts (2) the rms speed s m M
RT v rms /4803≈= ………………… 3pts (3) the internal energy RT i E 2
= ………………… 1pts For O 2, i = 5, ………………… 1pts the internal energy 60912≈=
RT i E J ………………… 2pts 14(10pts)
(1) 1→2: Isothermal expansion )/ln(
12V V nRT Q H H = ………………… 2pts 3→4: Isothermal compression )/ln(
34V V nRT Q L L = ………………… 2pts (2) 2→3: Adiabatic expansion 1312
--=γγV T V T L H ………………… 1pts
4 1: Adiabatic compression. 1411--=γγV T V T L H ………………… 1pts Therfore, 4
312V V V V = ………………… 1pts H
L H L T T Q Q = ………………… 1pts The efficiency of Carnot engine is H
L H L T T Q Q -=-=11η ………………… 2pts 15 (17pts)
(1) The light path difference is
θδs i n
d = ………………… 2pts For bright fringes
λθδm d ==s i n
………………… 2pts The separation between the 2nd-order bright fringe and the 3rd-order bright fringe is
423105.523tan tan -⨯==-≈
-=∆d D d D d D D D x λλλθθm ………………… 3pts (2) The light path difference is
()L n d 1sin -+=θδ ……………………………………… 3pts
For bright fringes
()λθδm L n d =-+=1s i n …………………………… 1pts At the central, point θ=0 ……………………………………… 1pts
The central point on the viewing screen is now occupied by the seventh bright slid fringe (m =7) ()λδ710sin =-+=L n d ……………………………………… 1pts 61064.6)1/(7-⨯=-=n L λm ……………………………………… 2pts
(3) No ……………………………………… 2pts
16 (13pts)
(1) The period measured by the observers on the spaceship is the proper
time. ……………1pts
126.020==k
m T πs ……………4pts (2) The mass and the spaceship is moving at a very high speed relative to the Earth. The effect of special theory of relativity must be taken into account. ………2pts
The period measured by the observers on the Earth is not the proper
time. ……………2pts
According to the special theory of relativity,
209.0/1220=-=c v T T s ……………4pts。