# A model train, with a mass of #8 kg#, is moving on a circular track with a radius of #2 m#. If the train's kinetic energy changes from #8 j# to #36 j#, by how much will the centripetal force applied by the tracks change by?

##### 1 Answer

Nov 9, 2017

#### Answer:

The centripetal force increases by 28 N, from 8 N to 36 N.

Details follow.

#### Explanation:

Centripetal force is given by

For this train, we know the mass of the train,

Since the kinetic energy

which I will rewrite as

(because we will need

When the energy is 8 J,

and the centripetal force is

When the energy is 36 J,

and the centripetal force is

The change in centripetal force will be