Question

A model train, with a mass of `3 kg`, is moving on a circular track with a radius of `5 m`. If the train's kinetic energy changes from `32 j` to `12 j`, by how much will the centripetal force applied by the tracks change by?

Answer 1

`F_C = 2(KE)/r = 2 20/5 = 8 N`

Explanation:

Start by writing the equation for Kinetic Energy, KE:
`KE = 1/2 mv^2` divide by 2 on both sides
`2KE = mv^2` divide by r the radius of the circular track
`2(KE)/r = mv^2/r` now on the right what we have is the Centripetal Force `F_C = m(v^2/r)`, so:
`F_C = 2(KE)/r = 2 20/5 = 8 N`