Question

If an object with a mass of `3kg` changes speed from `4m/s` to `9m/s`, by how much does its kinetic energy change?

Answer 1

The kinetic energy will increase from 24 J to 121.5 J, an increase of 97.5 J.

Explanation:

Because kinetic energy is given by `1/2mv^2` regardless of the particular situation involved, the change in kinetic energy here will be

`DeltaK = 1/2mv_f^2-1/2mv_i^2 = 1/2 (3)(9)^2-1/2(3)(4)^2`

`DeltaK = 121.5 J - 24 J = 97.5 J`