近代物理作業 Chap1
班級:光電二甲
學號:497L0008
姓名:吳翊嘉
4. An observer on a spacecraft moving at 0.700C relative to the earth finds that a car
takes 40.0min to make a trip. How long does the trip take to the driver of the car？
t0
t＝
v2
1 2
c
t0
40  60 ＝
1
0.7c 2
c2
t 0 ＝2400  0.51 ＝1713.94(s)
23. A woman leaves the earth in a spacecraft that makes a round trip to the nearest
star，4 lights-years distant，at a speed of 0.9C. How much younger is she upon her
return than her twin sister who remained behind.
0.9c  ＝ 1 0.81 ＝ 0.19 ＝0.4358
v2
＝ 1
2
c2
c
2
1
4
＝0.4358
x
x＝9.17
9.17-4＝5.17(歲)
33. A particle has a kinetic energy 20 times its rest energy. Find the speed of the particle
in terms C.
KE＝20 E0
(r-1)m c 2 ＝20m c 2
1
1
2
-1＝20
v
c
1
c v
c2
2
2
＝21
1
＝441
c  v2
c2
2
441 c 2 -441 v 2 ＝ c 2
441 v 2 ＝ 440c 2
v＝ 0.9977c 2
v＝0.9988c