Question
(iii)The cyclist then uses the brakes on the bicycle to stop. Explain what happens to the kinetic energy of the cyclist.
Answer
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Ina
Professional · Tutor for 6 years
Answer
So, when the cyclist uses the brakes to stop the bicycle, the kinetic energy is getting transformed and dissipated mainly in the form of heat and a bit as sound energy.
Explanation
When the cyclist uses the brakes on the bicycle, he/she comes to a stop. But, according to the law of conservation of energy, the energy can't be destroyed - it only changes from one form to another. In this case, when the bike comes to a stop, the kinetic energy due to motion diminishes. But, this energy hasn't been destroyed. Instead, it goes through a transformation from one state to another. This dissipated kinetic energy is transformed mainly into two types. One is the form of heat, radiated due to the friction caused as a result of the rubbing of the brake shoes and the cycle rim. Although might be negligible, some of this kinetic energy ends up as sound energy. Possible grinding or squeaking sound when the brakes are applied is due to the same reason. In essence, it won't technically be accurate to say the kinetic energy disappears, but rather it is merely transformed into distinct types of energy.