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

As the person comes to rest at the end of the water slide, the gravitational potential energy is converted into kinetic energy as they slide down. When they reach the bottom and come to a stop, the kinetic energy is transformed into other forms of energy, primarily heat due to friction between the person and the slide, and also dissipated into the surrounding air and water. This loss of energy occurs because of energy transfer to the environment.

To calculate the work done against the force of friction, we should use the distance moved along the slope (hypotenuse), which is 6.3 m. This distance is important because the friction force acts along the slope as the box is pushed up. Using this distance allows for an accurate calculation of the work done, as the force of friction acts over the distance that the box travels.

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

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

First, convert the mass from grams to kilograms:

$58 ext{ g} = 0.058 ext{ kg}$

Now substituting the values into the equation:

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

Calculating:

$KE = 0.029 \times 784 = 22.736 ext{ J}$

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