A model train, with a mass of #3 kg#, is moving on a circular track with a radius of #5 m#. If the train's kinetic energy changes from #32 j# to #12 j#, by how much will the centripetal force applied by the tracks change by?

1 Answer
Feb 2, 2016

Answer:

#F_C = 2(KE)/r = 2 20/5 = 8 N#

Explanation:

Start by writing the equation for Kinetic Energy, KE:
#KE = 1/2 mv^2 # divide by 2 on both sides
#2KE = mv^2 # divide by r the radius of the circular track
#2(KE)/r = mv^2/r# now on the right what we have is the Centripetal Force #F_C = m(v^2/r)#, so:
#F_C = 2(KE)/r = 2 20/5 = 8 N#