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  GR8677 #70
Problem
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Verbatim question for GR8677 #70
Special Relativity}Length Contraction

One deduced the approximate value of \gamma in Problem 69 (as well as the equation for length contraction). Thus, 4=\gamma L_{moving}\Rightarrow L_{moving}=4\times 3/5=12/5=2.4. This is choice (A).

See below for user comments and alternate solutions! See below for user comments and alternate solutions!
Alternate Solutions
Saybrook
2014-09-24 18:51:52		Isn't it this simple?
(rest length of car)/(relative length of car)=(rest length of garage)/x
where you solve for x which is the relative length of the garage in the car's rest frame.
5/3=4/x => x=12/5=2.4		Alternate Solution - Unverified
Comments
Saybrook
2014-09-24 18:51:52		Isn't it this simple?
(rest length of car)/(relative length of car)=(rest length of garage)/x
where you solve for x which is the relative length of the garage in the car's rest frame.
5/3=4/x => x=12/5=2.4
Saybrook
2014-09-24 18:54:17		 Nevermind this is exactly what Yosun wrote; I just glanced at it.
Alternate Solution - Unverified
Mindaugas
2007-09-28 08:00:11		Answer A is also the only one which is smaller than 4 m.
neon37
2010-11-03 12:13:13		 Yep! think about the term "length contraction" and relative velocity and reference frames. In the car's reference frame, the garage is moving. So the length of the garage has to contract, which means smaller than 4, and A is the only one.
NEC

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