Question

If an object with a mass of `3kg` changes speed from `5m/s` to `6m/s`, by how much does its kinetic energy change?

Answer 1

`"16.5 J"`

Explanation:

Kinetic energy is given by

`"K" = 1/2\ "mv"^2`

`"K"_1 = 1/2\ "mv"_1^2`

`"K"_2 = 1/2\ "mv"_2^2`

Subtract first equation from second

`"K"_2 - "K"_1 = 1/2\ "mv"_2^2 - 1/2\ "mv"_1^2`

`color(blue)(Delta"K" = 1/2\ "m"["v"_2^2 - "v"_1^2])`

Plug in the values

`Δ"K" = 1/2 × "3 kg" × [("6 m/s")^2 - ("5 m/s")^2] = color(green)"16.5 J"`