A model train, with a mass of #4 kg#, is moving on a circular track with a radius of #3 m#. If the train's kinetic energy changes from #15 j# to #6 j#, by how much will the centripetal force applied by the tracks change by?

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Answer 1 · 2016-09-11T09:19:47

the centripetal force change from 10n to 4n, or decrease at 2,5 times.

Kinetic energy is #(mv^2)/2#

The first velocity #v_1=sqrt(15*2/4)=sqrt(7,5)#

#v_2=sqrt(6*2/4)=sqrt3#

The centripetal force is #F=mv^2/r#

#F_1=4*7,5/3=10n#
#F_2=4*3/3=4n#