During braking

PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

During braking, an eddy-current brake exerts a constant retarding force of

3.0\times10^{3}\,\text{N}

on a train wheel whose rim is moving at a steady speed of

20\,\text{m s}^{-1}

. Assuming the force remains constant for

10\,\text{s}

, how much electrical energy is converted into heat in the wheel during this interval? (a)

9.0\times10^{5}\,\text{J}

(b)

6.0\times10^{5}\,\text{J}

(c)

3.0\times10^{5}\,\text{J}

(d)

1.2\times10^{6}\,\text{J}