ps1soln

# In the friends frame the door closes and then hits

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Unformatted text preview: hat the two events are spacelike separated, and, hence, acausal. They happen in a diﬀerent order in the two diﬀerent frames. In the friends frame, the door closes and then hits the front. In the runner’s frame, when the pole hits the front, the door to the barn is still open. We can show this rigorously using the formulae for Lorentz transformations. In the friend’s frame the events happen Barn door closes: (t1 , x1 ) = (0, 0) Pole hits front: (t2 , x2 ) = (3.75 m, 15 m) (13) In the runners frame, these events happen as ¯¯ Barn door closes: (t1 , x1 ) = (0, 0) ¯¯ Pole hits front: (t2 , x2 ) = (−13.75 m, 20 m) (14) i.e. the barn door is still open when the pole hits the front in the runner’s frame. Of course, we can ask what happens in the runner’s frame once the pole front hits the barn. Let’s assume it can come to immediate rest. It takes ﬁnite time for the front of the pole to communicate the stop” message to the back of the pole. Assuming the pole is not completely r...
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## This document was uploaded on 02/28/2014.

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