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*must be correct for thumbs up* Imagine that a relativistic train travels past y

ID: 1500591 • Letter: #

Question

*must be correct for thumbs up*

Imagine that a relativistic train travels past your lecture room at a speed of 0.934 c. The passengers of the train claim that when they measure the length of the train using standard meter bars found on the train, the length comes out to be 87.0 m. What would be the length of the train in the frame of the lecture room if you measured it?
(in m)

How long would a regular 50 minute long class in the lecture room last for the passengers of the train if they measured it while sitting on the train?
(in min)

A: 1.32×101 B: 1.49×101 C: 1.69×101 D: 1.91×101 E: 2.15×101 F: 2.43×101 G: 2.75×101 H: 3.11×101

Explanation / Answer

1) H) 3.11*10^1 m

given

Lo = 87 m

v = 0.934c

use length contraction equation

L = Lo*sqrt(1 - (v/c)^2

= 87*sqrt(1 - (0.934*c/c)^2)

= 87*sqrt(1 - 0.934^2)

= 31.1 m or 3.11*10^1 m

2) C) 1.4*10^2 minutes

now use time dialation equation

deta_t = delta_to/sqrt(1 - (v/c)^2)

= 50/sqrt(1 - 0.934^2)

= 140 minutes

= 1.4*10^2 minutes