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1. A child of 40kg rides a 35kg bike at 9.0ms−1. The brakes are then applied and the bike is slowed to 3.8ms−1. How much work is done by frictional forces?

I've been stuck on this question for ages and I don't understand how to find work done when the distance is not given. Is anyone able to help me out with this question?
2. Use the Kinetic Energy equation to compare the kinetic energy before brakes are applied and the Kinetic energy after brakes are applied.

The question wants you to assume that the Energy lost is only due to the friction from the brakes.

The difference in Kinetic energies will obviously be the frictional force..................

#dab
3. (Original post by Bulletzone)
Use the Kinetic Energy equation to compare the kinetic energy before brakes are applied and the Kinetic energy after brakes are applied.

The question wants you to assume that the Energy lost is only due to the friction from the brakes.

The difference in Kinetic energies will obviously be the frictional force..................

#dab
Thank You! I was sure I'd tried this but obviously I hadn't.

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