This question is about energy changes - Edexcel - GCSE Physics Combined Science - Question 4 - 2021 - Paper 1

As the person comes to rest after the end of the water slide, the gravitational potential energy that was converted into kinetic energy during the slide is dissipated. This energy is transferred to the surroundings, primarily through friction with the slide and air resistance. Some energy may also be transformed into thermal energy due to the friction between the person's body and the slide, leading to a slight rise in temperature.

To calculate the work done against the force of friction between the box and the slope, the distance moved in the direction of the frictional force should be considered. In Figure 9, this is represented by the length of the slope (hypotenuse), which allows us to account for the work done against friction as the box moves upwards along the slope.

To calculate the kinetic energy (KE) of the tennis ball, we use the equation:

$KE = \frac{1}{2} \times m \times v^2$

Where:

• Mass, m = 58 g = 0.058 kg (converted to kg)
• Velocity, v = 28 m/s

Substituting the values:

$KE = \frac{1}{2} \times 0.058 \times (28)^2$

Calculating:

$KE = \frac{1}{2} \times 0.058 \times 784 = 22.736 \text{ J}$

Therefore, the kinetic energy of the tennis ball is approximately 23 J.