006 (part 1 of 2) 10.0 points Suppose the speed of light were 100 mph. Trains on

Question

006 (part 1 of 2) 10.0 points Suppose the speed of light were 100 mph. Trains on parallel tracks are approaching each other at speeds of 90 mph and 84.92 mph. A person on one of the trains sees the two trains approaching each other at what speed? Answer in units of mph. 007 (part 2 of 2) 10.0 points After the trains pass a crazy person on the 90 mph train fires a rifle with muzzle velocity 90 mph back at the other train. With what speed does the person on that train see the bullet approach? (A negative answer means the bullet is receding). Answer in units of mph.

Explanation / Answer

In relativity, the frame of each of the rockets has a different clock rate and distance measure, and the notion of simultaneity in the direction of motion is altered, so the addition law for velocities is changed and can also be called the composition law for velocities. For collinear motions, the velocity of one rocket wrt the passenger on another rocket is given by: S=(U+V)/(1+(V/c)(U/c)) = (90+84.92)/[1+(90/100)*(84.92/100)] = 99.14 mph
Nothing goes faster then c, and doesn't even appear so

b) The speed of the bullet is 0
so the answer is 84.92 mph, receeding

S = (84.92+0)/(1+84.92*0/c²) = 84.92

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