Suppose you measure the density (mass per volume)of an object moving by you at very high speed.How will its density compare to the density it would have at rest in your reference frame?
A)Its density would be lower.
B)Its density would be higher.
C)Its density would be the same.
D)There is no way to know,because relativity doesn't tell us anything about density.

Question

Quizplus · Accepted Answer

According to the theory of relativity, as an object moves at a very high speed, its length contracts in the direction of motion. However, its mass is considered to increase (relativistic mass increase), and since density is mass per unit volume, and the volume decreases due to length contraction without a decrease in the amount of matter, the density of the object would appear to be higher to an observer in a different frame of reference.

Suppose You Measure the Density (Mass Per Volume)of an Object