Question

A rocket is moving up with a velocity v. if the velocity of this rocket is suddenly tripled what will be the ratio of two kinetic energies?

Answer 1

The ratio will be 1:9 because K.E is directly proportional to the square of the velocity

Answer 2

For, 1st case
Let the mass of the rocket be m
velocity be v
then, Kinetic energy= 1/2mv2

For, 2nd case,

mass of the rocket= m
velocity= 3v
then, Kinetic Energy= 1/2*m*(3v)2
1/2m9v2

Now, ratio of both kinetic energy= 1/2mv2 / 1/2m9v2
=1/9
=1:9