This question is about energy changes - Edexcel - GCSE Physics - Question 6 - 2021 - Paper 1

As the person comes to rest after exiting the water slide, the gravitational potential energy initially gained is transformed mainly into kinetic energy as they travel down the slide. However, upon reaching the end of the slide and coming to a rest, this kinetic energy is converted into other forms of energy, primarily thermal energy due to friction between the person and the slide, as well as the surrounding air. Consequently, the energy dissipates into the surroundings.

To calculate the work done against the force of friction, we must consider the distance that the box moves along the slope, which must be the actual path taken. In Figure 12, this distance is the length of the slope itself (6.0 m), as the work done against friction is dependent on this distance, rather than the vertical height or horizontal distance.

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

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

First, we need to convert the mass from grams to kilograms:

$m = 58 g = 0.058 kg$

Now, substituting in the values:

$KE = \frac{1}{2} (0.058 \text{ kg}) (28 \text{ m/s})^2$

Calculating the kinetic energy:

$KE = \frac{1}{2} \times 0.058 \times 784$ $KE = 22.752 \text{ J}$

Thus, the kinetic energy of the tennis ball is approximately 22.75 J.