The UK uses renewable energy resources to generate some of its electricity - AQA - GCSE Physics - Question 4 - 2023 - Paper 1

Using the equation for gravitational potential energy:

$E_p = \text{mass} \times \text{gravitational field strength} \times \text{height}$
Substituting the provided values:
$E_p = 2,500,000 \text{ kg} \times 9.8 \text{ N/kg} \times 15.0 \text{ m}$
Calculating this, we find:
$E_p = 367,500,000 \text{ J}$.

The equation linking energy, power, and time is:
$E = P \times t$.

First, convert 60 minutes to seconds:
$t = 60 \text{ minutes} \times 60 \text{ seconds/minute} = 3600 \text{ seconds}$
Then, using the power of the generator:
$E = 3000 \text{ W} \times 3600 \text{ s} = 10,800,000 \text{ J}$.

The power output varied because the level of water in the river varies, which can be influenced by factors such as seasonal rainfall patterns and evaporation rates. Typically, water levels are lower in the summer months, reducing the potential energy available for the generator.