# A model train, with a mass of #4 kg#, is moving on a circular track with a radius of #15 m#. If the train's kinetic energy changes from #18 j# to #12 j#, by how much will the centripetal force applied by the tracks change by?

##### 1 Answer

Mar 19, 2016

#### Answer:

**Change in force :**

#### Explanation:

The key thing in this question is to determine the change in velocity because the centripetal force depends on velocity.

We can use the initial & final kinetic energies to determine initial and final velocities. And then determine the change in force.

(I'm actually going to take a shortcut and determine

**Initial**

**Final**

**Change in force :**