Question

If an object with a mass of `2 kg` changes speed from `9 m/s` to `12 m/s`, by how much does its kinetic energy change?

Answer 1

The change in kinetic energy is `=63J`

Explanation:

The kinetic enegy is

`KE=1/2mv^2`

The change in kinetic energy is

`DeltaKE=1/2mv^2-1/2mu^2=1/2m(v^2-u^2)`

The mass is `m=2kg`

The initial speed is `u=9ms^-1`

The final speed is `v=12ms^-1`

The cgange in kinetic energy is

`DeltaKE=1/2*2*(12^2-9^2)=63J`