Question

When the velocity of an aeroplane is doubled, the momentum ___________

(a) Remains unchanged

(b) Is conserved

(c) Becomes zero

(d) Increases uniformly

This question was addressed to me in an interview for job.

My doubt stems from Conservation of Energy topic in division Laws of Motion of Engineering Physics I

Answer 1

The correct option is (b) Is conserved

To elaborate: If velocity of the aeroplane is doubled, its momentum is also doubled. However, combined momentum of air and aeroplane is conserved. As the momentum of aeroplane increases, the momentum of air also increases by an equal amount in the opposite direction.