A boxcar without a front or a back is moving toward the right.Two electrons move through the boxcar,one moving from back to front toward the right,the other moving from front to back toward the left.According to me,each electron is moving with a speed of 0.8c,and the boxcar is moving with a speed of 0.6c.A passenger in the boxcar records how long it takes each electron to pass from one end of the boxcar to the other end.According to the passenger,which took longer?
A)the electron going from back to front
B)the electron going from front to back
C)They both took the same time.
D)Since nothing can go faster than light,an electron cannot move toward the left with a speed of 0.8c through a boxcar moving toward the right with a speed of 0.6c.

Question

Quizplus · Accepted Answer

The time taken by each electron to traverse the boxcar will appear different to the passenger due to relativistic effects. Specifically, the velocities of the electrons relative to the boxcar are not simply additive or subtractive because of the relativistic velocity addition formula. For the electron moving from back to front (toward the right, in the same direction as the boxcar), its speed relative to the boxcar is less than 0.8c when corrected for relativistic effects. For the electron moving from front to back (toward the left, opposite to the boxcar's direction), its speed relative to the boxcar is also adjusted by relativistic effects but in a manner that makes its effective speed in the boxcar's frame slower than the first electron's effective speed. Thus, due to these relativistic adjustments, the electron moving from back to front effectively travels faster relative to the boxcar and takes less time to cross it than the electron moving from front to back, making the latter take longer from the passenger's perspective.

A Boxcar Without a Front or a Back Is Moving