A cyclist is riding a bicycle at a steady velocity of 12 m/s - Edexcel - GCSE Physics - Question 3 - 2018 - Paper 1

When the cyclist uses the brakes to stop, the kinetic energy of the cyclist and bicycle decreases. This energy does not just disappear; rather, it is transformed into thermal energy. As the brakes are applied, friction occurs between the brake pads and the bicycle wheels, which generates heat. Consequently, the thermal energy (or heat) in the brakes increases, as the energy from motion is converted into heat.

To find the average force, we use the formula:

$Work = Force \times Distance$

Rearranging gives:

$Force = \frac{Work}{Distance}$

Substituting the values:

$Force = \frac{1600 \text{ J}}{28 \text{ m}} \approx 57.14 \text{ N}$

Thus, the average force exerted by the cyclist is approximately 57 N.

To determine the average power for each session, we use the formula:

$Power = \frac{Energy}{Time}$

For session 1:

$Power_1 = \frac{45.2 \text{ kJ}}{300 \text{ s}} = 0.1507 \text{ kW}$

For session 2:

$Power_2 = \frac{37.9 \text{ kJ}}{300 \text{ s}} = 0.1263 \text{ kW}$

Therefore, the displays indicate that the athlete developed more power during the first session compared to the second session.