An object moves in a direction parallel to its length with a velocity that approaches the velocity of light. The mass of this object as measured by a stationary observer
A) does not change.
B) increases slightly.
C) approaches zero.
D) approaches infinity.

Question

Quizplus · Accepted Answer

According to the theory of relativity, as the velocity of an object approaches the speed of light, its relativistic mass increases and theoretically approaches infinity. This is because the object's energy increases with velocity, and mass and energy are equivalent as stated in Einstein's equation E=mc^2.

An Object Moves in a Direction Parallel to Its Length