Figure 4 shows a sailing boat crossing an ocean - AQA - GCSE Physics Combined Science - Question 3 - 2021 - Paper 1

1. The generator can still charge the battery if the wind turbine is not operational due to lack of wind.
2. Using the generator ensures a constant power supply even when renewable sources are intermittent.

The combustion of fossil fuels releases carbon dioxide into the atmosphere, contributing to global warming and the greenhouse effect.

To calculate the speed, we can use the formula for kinetic energy: $KE = \frac{1}{2} mv^2$ Substituting the values we have: $81000 = \frac{1}{2} \times 8000 \times v^2$ Rearranging for $v$ gives us: $v^2 = \frac{81000 \times 2}{8000}$. Calculating this yields $v = 4.5$ m/s.

Using the formula for potential energy: $PE = mgh$ We can rearrange it to find height: $h = \frac{PE}{mg}$. Substituting the values: $h = \frac{19600}{8000 \times 9.8}$. Calculating this gives us $h = 0.25$ m.