When an object moves close to the speed of light relative to Earth, what happens to its dimensions compared to what they were before it began moving, as measured by an Earth-based observer?
A) Only lengths perpendicular to the direction of travel are decreased.
B) Only lengths parallel to the direction of travel are decreased.
C) All lengths are decreased.
D) No lengths are affected.

Question

Quizplus · Accepted Answer

According to the theory of relativity, lengths parallel to the direction of travel are contracted (Lorentz contraction) when an object moves at speeds close to the speed of light relative to an observer. Lengths perpendicular to the direction of travel are not affected.

When an Object Moves Close to the Speed of Light