Aspaceship is moving past us at a speed close to the speed of light. if we could measure the mass of the spaceship as it goes by, what would it be?

the mass of the space ship would be greater than its mass when at rest, it's mass becomes so high that it reaches infinity.

Explanation:

From Einstein's relativity equation E=, where E is energy, m is mass and C is the speed of light, the equation shows that energy (E) and mass (m) are interchangeable because there are different forms of the same thing if mass is somehow converted into energy (just as in the atomic bomb). This equation shows that mass increases with speed (as an object moves, its mass increases), and if an object were to move close to the speed of light (the fastest speed a particle can move in a vacuum) its mass would increase that in reaches infinity.

explanation: in any substance/object, the particles inside it (atoms/molecules) constantly move in random directions and with random speeds (this motion is called brownian motion). as a result, the particles have some kinetic energy (which is proportional to the temperature of the substance).

explanation:

have a great day!