Combined Physics - P1 Energy

Question 1

In physics, what is a ‘system’?

Answer 1

A group of objects

Question 2

What are the four ways in which energy can be transferred?

Answer 2

1. Mechanically (by a force doing work)
2. Electrically (work done by moving charge)
3. Heating
4. Radiation (light and sound)

Question 3

What is work done the same as?

Answer 3

Energy transferred

Question 4

What equation links kinetic energy, mass and velocity?

Answer 4

Ek = 0.5 x m x v²

Kinetic energy = 0.5 x mass x velocity²

Question 5

Name the 8 energy stores.

Answer 5

1. Thermal
2. Kinetic
3. Gravitational Potential
4. Elastic Potential
5. Chemical
6. Magnetic
7. Electrostatic
8. Nuclear

Question 6

What is a closed system?

Answer 6

A system where matter or energy cannot leave or enter.

Question 7

What equation links gravitational potential energy, mass, gravitational field strength and height?

Answer 7

Ep = m g h

Gravitational Potential Energy = mass x gravitational field strength x height

Question 8

Describe the energy changes involved in a falling ball.

Answer 8

The ball’s gravitational potential energy store decreases.

The ball’s kinetic energy store increases.

Question 9

What are the units for work done?

Answer 9

Joules

Question 10

What is specific heat capacity?

Answer 10

The amount of energy required to raise the temperature of 1 kg of the substance by 1 ^oC.

Question 11

What equation links power, energy transferred and time?

Answer 11

Power = Energy Transferred / Time

(P = E/t)

Question 12

What equation links power, work done and time?

Answer 12

Power = Work done / Time

(P = W/t)

Question 13

Name the energy stored in a stretched or compressed spring.

Answer 13

Elastic potential energy

Question 14

What does ‘conservation of energy’ mean?

Answer 14

Energy can be transferred, stored or dissipated, but can never be created or destroyed.

Question 15

Describe the energy transfer involved in a person lifting a weight.

Answer 15

• The person’s chemical energy store decreases.
• The kinetic energy store of the person’s arm and the weight increases.
• The gravitational potential energy store of the person’s arm and the weight increases.

Question 16

Describe the energy transfer when work is done by friction.

Answer 16

Kinetic energy store of the object decreases.

Thermal energy store of the surroundings increases.

Question 17

A book on the top shelf has a gravitational potential energy store of 100 J. The book falls. How much energy will be in the book’s kinetic energy store as it hits the ground?

Answer 17

100 J

Question 18

What is another name for ‘wasted’ energy?

Answer 18

Dissipated energy

Question 19

What are lubricants used for?

Answer 19

Reduce friction between moving objects.

Question 20

List some examples of house insulation.

Answer 20

• Cavity wall insulation (reduces convection)
• Loft insulation (reduces convection)
• Double-glazed windows (reduces conduction)
• Draught excluders (reduces convection)

Question 21

Describe how energy is transferred by convection.

Answer 21

• Particles gain energy
• Particles move further apart
• The fluid becomes less dense
• Particles rise and transfer energy to other particles
• The fluid becomes more dense
• Particles fall
• A convection current is formed

Question 22

What equation links efficiency, useful power output and total power input?

Answer 22

efficiency = useful power output / total power input

Question 23

Why are homes insulated?

Answer 23

To reduce heat loss

Question 24

Describe how energy is transferred by conduction.

Answer 24

• Particles vibrate more
• Particles collide with neighbouring particles
• Transferring energy

Question 25

To insulate a house, would you want the insulation to have a high or low thermal conductivity?

Answer 25

Low thermal conductivity (to reduce heat loss)

Question 26

What equation links efficiency, useful output energy transfer and total input energy transfer.

Answer 26

efficiency = useful output energy transfer / total input energy transfer

Question 27

List seven renewable resources

Answer 27

* Bio-fuel * Wind * Hydro-electricity * Geothermal * Tidal * Solar * Water waves

Question 28

Name four non-renewable resources

Answer 28

* Coal * Oil * Gas * Nuclear

Question 29

What do you call energy resources that do not run out?

Answer 29

Renewable

Question 30

Name the two gases that can be released by burning fossil fuels and the environmental problems they cause.

Answer 30

Carbon dioxide – global warming Sulfur dioxide – acid rain

Question 31

**Higher Q**. Give three ways the efficiency of an energy transfer be increased.

Answer 31

* Insulation * Lubrication * More streamlined

Question 32

List the three types of fossil fuel

Answer 32

* Coal * Oil * Gas

Question 33

Name three energy resources that are _not_ reliable.

Answer 33

* Wind * Wave * Solar

Question 34

Describe how solar cells work and give some advantages and disadvantages.

Answer 34

Solar cells absorb light energy and transfer it into electrical energy. (+) Do not produce CO₂ (+) Expensive to buy and install (+) Useful in remote places – can be used on a small scale to power road signs. (-) Not reliable – only work when sunny (-) They do not produce electricity at night

Question 35

Describe how electricity is produced using hydroelectric power and give some advantages and disadvantages.

Answer 35

* Water collected in a large dam/reservoir * Water falls from a height and falls through turbines * The turbines drive a generator that generates electricity. (+) Doesn’t produce CO₂ or other pollutants. Can immediately generate electricity to meet sudden surges in demand for electricity. (-) High initial costs, damage to the environment, habitat loss, visual pollution.

Question 36

Describe how electricity is produced using tidal power and give some advantages and disadvantages.

Answer 36

* A tidal barrage is built across an estuary. * The tides are produced by the gravitational pull of the Sun and Moon. * As the tide comes in/out, it builds up behind the barrage and is then released through the barrage at a controlled speed. * As the water moves through, it turns turbines that turn a generator to produce electricity. (+) reliable – two tides every day, doesn’t produce CO₂ or other pollutants. (-) high installation costs, damage to wildlife, visual pollution, prevents access to boats

Question 37

Give three disadvantages of nuclear power.

Answer 37

* Lots of nuclear waste is produced * Risk of major catastrophe * High cost of building power plant

Question 38

Describe how electricity is produced using geothermal power and give some advantages and disadvantages.

Answer 38

* Water is heated by naturally hot rocks underground. * Water is turned into steam. * The steam turns a turbine that drives a generator to generate electricity. (+) Reliable, doesn’t produce CO₂ or other pollutants (-) Not many suitable locations where hot rocks are close to the surface (-) High cost of building the power plant

Question 39

Describe how electricity is produced using wave power and give some advantages and disadvantages.

Answer 39

Waves turn turbines that turn a generator to produce electricity (or the wave movement compresses air and the air turns the turbine). (+) Doesn’t produce CO₂ or other pollutants (-) Spoils view, disturbs seabed and marine habitats

Question 40

Describe how electricity is produced using biofuels and give some advantages and disadvantages.

Answer 40

Plants and animal manure are used as a fuel. They are used in a power station to heat water. The water turns to steam which turns a turbine that drives a generator and produces electricity. (+) carbon neutral (no net increase of CO₂) in atmosphere. Reliable because crops don’t take long to grow. (-) biodiversity loss in fields used to grow crops for biofuels. Deforestation to grow crops.

Question 41

List three energy resources that are reliable.

Answer 41

Any three from: * Biofuels * Fossil Fuels (coal, oil, gas) * Nuclear * Geothermal * Tidal * Hydroelectric (except in droughts)

Question 42

Describe how you would measure the specific heat capacity of a block of metal (required practical).

Answer 42

* Measure the mass of the metal block. * Put a thermometer into the hole in the block and measure the starting temperature of the block. * Connect an immersion heater to a joulemeter and a power pack and place the heater into the metal block. * Insulate the block. * Heat the block for 5 minutes. * Calculate the temperature change of the block. * Read the joulemeter to calculate the energy transferred to the block. * Calculate specific heat capacity (c) using the following equation: c = E/(mθ)