Question

A model train, with a mass of `24 kg`, is moving on a circular track with a radius of `3 m`. If the train's kinetic energy changes from `18 j` to `21 j`, by how much will the centripetal force applied by the tracks change by?

Answer 1

2N

Explanation:

Mass of the train m= 24kg
The radius of circular path (r)=3m
Initial velocity,`v_1`
final velocity,`v_2`
Initial KE,`=1/2mv_1^2`
final KE,`1/2mv_2^2`
Change in KE =`1/2mv_2^2-1/2mv_1^2=21-18=3J`
Dividing both sides of this equation by radius (r)of circular path and multiplying both sides by 2 we have
`mv_2^2/r-mv_1^2/r=2*3/r`
We see that left side of the equation is the change in centripetal force
So The change in centripetal force is `=2*3/r=2.3/3(N.m)/m=2N`