A model train, with a mass of $16 k g$ $16 kg$ , is moving on a circular track with a radius of $3 m$ $3 m$ . If the train's kinetic energy changes from $15 j$ $15 j$ to $9 j$ $9 j$ , by how much will the centripetal force applied by the tracks change by?

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Answer 1 · 2017-03-23T14:45:11

The centripetal force changes by $= 4 N$ $=4N$

The centripetal force is

$F = \frac{m v^{2}}{r}$ $F=(mv^2)/r$

The kinetic energy is

$K E = \frac{1}{2} m v^{2}$ $KE=1/2mv^2$

The variation of kinetic energy is

$Delta KE=1/2mv^2-1/2m u^2$

$=1/2m(v^2-u^2)$

The variation of centripetal force is

$DeltaF=m/r(v^2-u^2)$

$DeltaF=2m/r1/2(v^2-u^2)$

$=(2)/r*1/2m(v^2-u^2)$

$=(2)/r*Delta KE$

$=2/3*(15-9)N$

$=4N$

A model train, with a mass of 16 kg16kg16 kg, is moving on a circular track with a radius of 3 m3m3 m. If the train's kinetic energy changes from 15 j15j15 j to 9 j9j9 j, by how much will the centripetal force applied by the tracks change by?