When the velocity of an object is doubled, by what factor is its momentum changed? by what factor is its kinetic energy changed?

Kinetic energy would increase by a factor of 4 where as momentum would increase by a factor of 2.

Explanation:

Kinetic Energy is given by 0.5*mass*velocity^2. Kinetic Energy is proportional to Velocity^2.

Momentum is given by mass*velocity. Momentum is proportional to Velocity.

If the velocity of an object is doubled, Kinetic energy would increase by a factor of 2^2 i.e 4 times. Momentum would increase by a factor of 2.

it would be kevlar ^^