Phy1 - Energy

Question 1

What is a system?

Answer 1

A group of objects

Question 2

What are the 4 ways energy can be transferred?

Answer 2

1) Mechanically (a force moving
2) Heating
3) Electrically (charge being transferred)
4) Radiation

Question 3

What is “work done” the same as?

Answer 3

Energy transferred

Question 4

What is the unit for work done?

Answer 4

Joules (J)

Question 5

What is the equation for kinetic energy?

Answer 5

Ek = ½ × m × v²
Kinetic energy = 0.5 × mass × velocity²

Question 6

What are the 8 energy stores?

Answer 6

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

Question 7

What is a closed system?

Answer 7

A system where matter or energy cannot enter or leave

Question 8

Describe the energy changes in a falling ball

Answer 8

The ball’s gravitational potential energy would decrease as it came closer to the ground.
The ball’s kinetic energy would increase as it speeds up

Question 9

What is specific heat capacity?

Answer 9

The amount of energy needed to increase 1kg of a substance by 1⁰C

Question 10

What is the equation for power?

Answer 10

P = E ÷ T
Power = Energy transferred ÷ time
or
P = WD ÷ T
Power = Work Done ÷ time

Question 11

Name the energy store in a streched or compressed spring

Answer 11

Elastic potential energy

Question 12

What does “conservation of energy” mean?

Answer 12

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

Question 13

Describe the energy transfer involved in a person lifting a weight

Answer 13

• 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 14

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 14

100 J

Question 15

What is another name for “wasted energy?”

Answer 15

Dissipated energy

Question 16

What are lubricants used for?

Answer 16

To reduce friction between moving objects

Question 17

List some examples of house insulation

Answer 17

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

Question 18

Describe how energy is transferred by convection

Answer 18

• 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 19

What is the equation for efficiency?
(power output)

Answer 19

Efficiency = Useful power output ÷ Total power output

Question 20

Why are homes insulated?

Answer 20

To reduce heat loss

Question 21

Describe how energy is transferred using conduction

Answer 21

• Particles vibrate more
• Particles bump into eachother
• This exchanges energy

Question 22

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

Answer 22

Low (to reduce heat loss)

Question 23

What is the equation for energy transferred?
(energy output)

Answer 23

Energy transferred = Useful output energy transferred ÷ Total input energy transferred

Question 24

List 7 renewable energy stores

Answer 24

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

Question 25

List 4 non-renewable energy sources

Answer 25

• Coal • Oil • Nuclear • Gas

Question 26

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

Answer 26

Renewable

Question 27

Name 2 gases that can be releases when burning fossil fuels and the problems they cause to the environment

Answer 27

Carbon dioxide - Global warming Sulfur dioxide - Acid rain

Question 28

What are the 3 types of fossil fuels?

Answer 28

• Coal • Oil • Gas

Question 29

Which 3 energy stores are not reliable?

Answer 29

• Wind • Waves • Solar

Question 30

Describe how solar cells work and give some advantages and disadvantages

Answer 30

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 31

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

Answer 31

• 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 32

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

Answer 32

• 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 33

Give 3 disadvantages of nuclear power

Answer 33

• Lots of nuclear waste is produced • Risk of major catastrophe • High cost of building the plant

Question 34

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

Answer 34

• 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 35

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

Answer 35

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 COz or other pollutants (-) Spoils view, disturbs seabed and marine habitats

Question 36

Describe how energy is produced using biofuels and give some advantages and disadvantages

Answer 36

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 Srow (-) biodiversity loss in fields used to grow crops for biofuels Deforestation to grow crops.

Question 37

List 6 energy sources that are reliable

Answer 37

• Biofuels • Fossil Fuels (coal, oil, gas) • Nuclear • Geothermal • Tidal • Hydroelectric

Question 38

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

Answer 38

• Measure the mass of the metal • 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/(m0)