A model train, with a mass of $2 kg$ , is moving on a circular track with a radius of $4 m$ . If the train's kinetic energy changes from $16 j$ to $0 j$ , by how much will the centripetal force applied by the tracks change by?

Question

1301 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-03-01T16:36:12

$8$ Newtons

We can use kinetic energy formula to get the speed of the train before and after the kinetic energy change:

$v=sqrt((2E)/m)$
$-> v = sqrt((2*16)/2)=sqrt(16)=4$

So we know the train was travelling at $4 ms^-1$

The kinetic energy at the end is $0J$ so the train has obviously came to rest.

The centripetal force required at $4ms^-1$ :

$F = (mv^2)/r$
$-> F =(2*(4^2))/4=8N$

And the centripetal force required when the train is at rest is just $0N$ . Thus the change in change in centripetal force is $8-0=8N$

A model train, with a mass of 2 kg2 kg, is moving on a circular track with a radius of 4 m4 m. If the train's kinetic energy changes from 16 j16 j to 0 j0 j, by how much will the centripetal force applied by the tracks change by?