If we could observe a spacecraft actually traveling past us at the speed of light, we would measure its mass to be
A) zero
B) slightly greater
C) infinite
D) the same as at rest

Question

Quizplus · Accepted Answer

According to the theory of relativity, as an object approaches the speed of light, its mass appears to increase from the perspective of an observer, theoretically reaching infinity at the speed of light. This is because the object's kinetic energy increases its mass.

If We Could Observe a Spacecraft Actually Traveling Past Us