National and global energy resources

Figure 8 shows apparatus set up to investigate the speed of a falling object.

The object is dropped from rest at the position shown. The object falls through the light gate.

The speed of the object, after it has fallen through a height, h, is measured by the light gate.

Label Figure 8 to show the height, h. Your label should look like this

The speed is measured at least four times for each drop height.

Give one reason for repeating the measurements.

The metre rule shown in Figure 8 is used to measure the height, h.

Suggest two ways to make the measurement of h as accurate as possible.

As the object in Figure 8 falls, energy is transferred.

These energy transfers are represented in Figure 9.

Complete the labels of the energy stores involved.

Figure 10 shows wind power generation from the year 2000 onwards.

Estimate the percentage change in wind power generation from 2005 to 2020.

percentage change =_........

Figure 17 shows a football kicked against a wall.

The football has a mass of 0.42 kg.

The football gains 11 J of gravitational potential energy as it moves from the ground to the wall.

Calculate the height at which the ball hits the wall.

Gravitational field strength = 10 N / kg

Use the equation

∆ GPE = m × g × ∆ h

Calculate the kinetic energy of the football when it is moving at a velocity of 12 m / s.

Use the equation

Describe the energy transfers that happen when the ball hits the wall.

*(b) In the UK, electricity is generated using non‑renewable and renewable energy resources.

The graph in Figure 18 shows how the amount of electricity generated by these resources changed from 2012 to 2020.

30

25

20

time in years from 2012 to 2020

Figure 18

Explain how and why the amount of electricity generated by renewable and non-renewable energy resources has changed from 2012 to 2020.

Your answer should include

• the trends shown in Figure 18

• the change in the amount of electricity generated by at least one renewable resource

• the change in the amount of electricity generated by at least one non‑renewable resource.

Figure 13 shows wind turbines, used to generate electricity for the National Grid.

The wind turns the turbine blades.

The wind is a renewable source of energy.

State two other renewable sources of energy.

For one turbine

• the energy input per second from the wind is 6.2 kJ

• the energy output per second to the National Grid is 2.2 kJ.

Calculate the efficiency of this turbine.

Suggest a reason why it is impossible for the turbine to use all the kinetic energy of the wind.

*(b) Nuclear fission and nuclear fusion are two non-renewable sources of energy.

Compare nuclear fission and nuclear fusion as possible sources of energy for generating electricity using a nuclear reactor.

Your comparison should refer to

• the differences between nuclear fission and nuclear fusion

• the relative advantages and difficulties involved in using these sources.

Use words from the box to complete the sentences about nuclear fission of uranium‑235 (U‑235).

A neutron hits a nucleus of U‑235 and causes the nucleus to_........ .

Each fission releases energy, two daughter nuclei and some_........ .

In a nuclear reactor, one fission can set off a controlled_........ reaction.

Both U‑235 and oil can be used as energy sources for generating electricity.

1 kg of natural uranium can result in the generation of 45 000 units of electricity.

1 kg of oil can result in the generation of 5.0 units of electricity.

Calculate the mass of oil needed to generate the same amount of electricity as 1 kg of natural uranium.

mass of oil =_........

Both using nuclear fuel and burning oil produce harmful waste products.

State one harmful waste product from each process.

using nuclear fuel_........

*(d) Figure 14 shows a household smoke alarm that uses radioactivity to detect smoke.

The radioactive source in the smoke detector is americium–241.

The table in Figure 15 shows some information about americium–241 and two other radioactive sources.

Explain why americium‑241 is the best of these three sources to use in this smoke detector.

Use information from Figure 15 and your own knowledge about radiation.

Your answer should refer to

• properties of alpha and gamma radiation

• half‑life.

A kettle is used to heat water.

Figure 11 shows a graph of temperature against time for the water in the kettle.

Calculate the rate of increase in temperature at a time of 150 s, by drawing a tangent to the curve in Figure 11 at a time of 150 s.

The kettle has an efficiency of 91% in supplying energy to the water. The thermal energy of the water increases by 3.3 × 10⁵J in 200 s.

Calculate the total amount of energy supplied to the kettle in the 200 s.

Use the equation

total amount of energy supplied =_........

*(c) The global demand for electricity is increasing.

There is a debate about whether nuclear power generation should or should not contribute to meeting this increasing demand.

Discuss the arguments for and against using nuclear power to meet the increasing global demand for electricity.

Figure 8 shows a helium nucleus.

Two of the particles in the helium nucleus are neutrons.

State the name of the other two particles in the helium nucleus.

Describe the difference between a fusion reaction and a fission reaction.

Nuclear fusion does not happen at low temperatures because of electrostatic repulsion between

The energy released per kilogram of fuel in a fusion reaction is 845 000 GJ.

The energy released per kilogram of fuel in burning oil is 0.0394 GJ.

Calculate the ratio of the energy released in fusion compared with the energy released in burning oil.

Use the equation

State two advantages of using a fusion reactor rather than burning oil in a power station.

State two of the difficulties that need to be overcome to produce a fusion reactor.

State two non‑renewable energy sources.

Figure 9 shows the renewable energy sources used in the UK in 2015.

Figure 9 is to scale.

State the energy source that gave the greatest amount of renewable energy for the UK in 2015.

Justify your choice of energy source in part (i).

State which of these energy sources gave about 20% of the energy from renewable sources for the UK in 2015.

Figure 10 shows all the energy sources used in Canada in 2014 and a

effect on the environment_........

effect on the environment_........

Figure 11 shows a wind turbine.

Explain how unwanted energy transfers could be reduced in the gear box.

Which of these is a non-renewable source of energy?

Explain why renewable sources provide an increasing fraction of the electricity supply for many countries.

Electricity can be generated using a water turbine.

Water gains kinetic energy by falling from the top of a dam.

Calculate the minimum height that 7.0 kg of water must fall to gain 1300 J of kinetic energy.

As water enters the turbine at the bottom of the dam, the kinetic energy of 8.0 kg of moving water is 1100 J.

Calculate the speed of the moving water as it enters the turbine.

Moving air can be used to generate electricity using a wind turbine.

Figure 8 is a graph of kinetic energy against wind speed for a mass of moving air.

Just before the air reaches a wind turbine it has a wind speed of 15 m/s.

When the air has gone through the turbine it has a wind speed of 13 m/s.

As the air moves through the turbine some of its kinetic energy is transferred to the turbine.

Use the graph to determine the percentage of the kinetic energy transferred to the turbine from the air.