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 $F=mv^2/r$

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

A model train, with a mass of 4 kg4 kg, is moving on a circular track with a radius of 3 m3 m. If the train's kinetic energy changes from 15 j15 j to 6 j6 j, by how much will the centripetal force applied by the tracks change by?