# frames of reference [duplicate]

Possible Duplicate:
Help Me Gain an Intuitive Understanding of Lorentz Contraction

Frames k and k' are inertial frames. Frame k' is moving at a velocity of magnitude v relative to frame k in the direction of the x-axis. there are rigid rods in each frame oriented along the direction of the relative velocity. Someone in frame k measures the rod that is stationary in k as having length L1 and the rod stationary in frame k' having a length L'2. What are the lengths of the rods measured by someone in frame k'?

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## marked as duplicate by Qmechanic♦, Manishearth♦, Waffle's Crazy Peanut, Sklivvz♦Dec 29 '12 at 15:18

The answer is length contraction, the lengths of the first is $L1\sqrt{1-v^2}$, it gets contracted, while the length of the moving one is $L2/\sqrt{1-v^2}$, so that after contraction it gives the right answer. The details of the geometry is explained in my answer here: What are the mechanics by which Time Dilation and Length Contraction occur? .