3. Figure 4 shows a hydroelectric power station.
Electricity is generated when water from the reservoir flows through the turbines.
i- Write down the equation which links density (ρ), mass (m) and volume (V).
[1 mark]
ANSWER
ii- The reservoir stores 6 500 000 m3 of water.
The density of the water is 998 kg/m3 .
Calculate the mass of water in the reservoir.
Give your answer in standard form.
[4 marks]
SOLUTION
iii- Write down the equation which links energy transferred (E), power (P) and time (t).
[1 mark]
ANSWER
iv- The electrical generators can provide 1.5 × 109 W of power for a maximum of 5 hours.
Calculate the maximum energy that can be transferred by the electrical generators.
[3 marks]
SOLUTION
Don’t forget to change time form hours to seconds. For that multiply 5 hrs by 60 minutes and 60 seconds. So time would be 5x60x60=180000 seconds.
v- Figure 5 shows how the UK demand for electricity increases and decreases during one day.
The hydroelectric power station in Figure 4 can provide 1.5 × 109 W of power for a maximum of 5 hours.
Give two reasons why this hydroelectric power station is not able to meet the increase in demand shown between 04:00 and 16:00 in Figure 5.
[2 marks]
ANSWER
It cannot provide energy required between 04:00 and 16:00 as demand is higher than 1.5×109 W.
Hydroelectric power station can only provide for 5 hours not 12 hours, whereas the demand remains high for longer than 5 hrs.
