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 energy is transferred from gravitational potential energy to kinetic energy as they slide down. Upon coming to rest, this kinetic energy is dissipated primarily due to friction and air resistance, converting the energy into thermal energy, which is then distributed to the surroundings, the water, or the slide.

The distance that should be used is the distance along the slope, which is given as 6.3 m. This is because the force of friction acts along this distance when the box is being pushed up the slope. The work done against friction depends on the distance moved in the direction of the force.

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

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

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

• Mass, m = 58 g = 0.058 kg.

Now substituting the values into the equation: $KE = \frac{1}{2} \times 0.058 \times (28)^2$

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

Therefore, the kinetic energy is approximately 23 J.