A model train, with a mass of #15 kg#, is moving on a circular track with a radius of #6 m#. If the train's kinetic energy changes from #40 j# to #27 j#, by how much will the centripetal force applied by the tracks change by?

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Answer 1 · 2018-01-27T02:27:36

#-4.3# Newtons.

We know that the centripetal force is given by

#F_c = (mv^2)/r#

We also know that kinetic energy is #E= 1/2mv^2#. We know that #2E = mv^2#, or #v^2 = (2E)/m#. Therefore:

#F_c = (m(2E)/m)/r#

#F_c = (2E)/r#

So

#DeltaF_c = (Delta 2E)/r#

Or

#DeltaF_c = (2(27))/6 - (2(40))/6#

#DeltaF_c = 9-40/3#

#DeltaF_c = -4.3 N#

Hopefully this helps!