A model train, with a mass of #24 kg#, is moving on a circular track with a radius of #3 m#. If the train's kinetic energy changes from #18 j# to #21 j#, by how much will the centripetal force applied by the tracks change by?

1 Answer
P dilip_k
Mar 5, 2016

2N

Explanation:

Mass of the train m= 24kg
The radius of circular path (r)=3m
Initial velocity,#v_1#
final velocity,#v_2#
Initial KE,#=1/2mv_1^2#
final KE,#1/2mv_2^2#
Change in KE =#1/2mv_2^2-1/2mv_1^2=21-18=3J#
Dividing both sides of this equation by radius (r)of circular path and multiplying both sides by 2 we have
#mv_2^2/r-mv_1^2/r=2*3/r#
We see that left side of the equation is the change in centripetal force
So The change in centripetal force is #=2*3/r=2.3/3(N.m)/m=2N#

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