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?

1 Answer
Mar 1, 2016

Answer:

#8# Newtons

Explanation:

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#