Question

A model train, with a mass of `15 kg`, is moving on a circular track with a radius of `6 m`. If the train's kinetic energy changes from `40 j` to `27 j`, by how much will the centripetal force applied by the tracks change by?

Answer 1

`-4.3` Newtons.

Explanation:

We know that the centripetal force is given by

`F_c = (mv^2)/r`

We also know that kinetic energy is `E= 1/2mv^2`. We know that `2E = mv^2`, or `v^2 = (2E)/m`. Therefore:

`F_c = (m(2E)/m)/r`

`F_c = (2E)/r`

So

`DeltaF_c = (Delta 2E)/r`

Or

`DeltaF_c = (2(27))/6 - (2(40))/6`

`DeltaF_c = 9-40/3`

`DeltaF_c = -4.3 N`

Hopefully this helps!