energy

Question 1

What are the 8 energy stores?

Answer 1

Thermal, Kinetic, Gravitational potential, Elastic potential, Chemical, Magnetic, Electrostatic, Nuclear

Question 2

How is energy transferred?

Answer 2

Mechanically, electrically, by heating or by radiation

Question 3

What is the difference between an open and closed system?

Answer 3

In a closed system, neither matter nor energy can enter or leave whereas in an open system, matter and energy can move freely in and out.

Question 4

What is the equation for work done?

Answer 4

work done = energy x displacement

Question 5

What is the equation for kinetic energy?

Answer 5

Kinetic energy = 1/2 mass x velocity^2

Question 6

What is the equation for gravitational potential energy?

Answer 6

Gravitational potential = mass x gravitational field strength x height

Question 7

What is the equation for elastic potential energy?

Answer 7

elastic potential energy = 1/2 spring constant x extension^2

Question 8

What is specific heat capacity?

Answer 8

The amount of energy required to raise the temperature of 1kg of a substance by 1 degree celsius

Question 9

What is the equation for specific heat capacity?

Answer 9

change in thermal energy = mass x specific heat capacity x temperature change

Question 10

Describe the specific heat capacity required practical

Answer 10

1. Measure the mass of the block and wrap in an insulating layer to prevent energy loss
2. Measure the initial temperature, set the P.D to 10V and start a stopwatch
3. Take readings of the temperature and current every minute for 10 minutes
4. Use the equation power=P.D x current to find the power and multiply it by time to find the energy
5. Use the specific heat capacity equation and repeat for other materials

Question 11

What is the law of conservation of energy?

Answer 11

Energy is not created nor destroyed, only transferred or stored.

Question 12

What is the equation linking power, energy and time?

Answer 12

power = energy / time

Question 13

What is the equation linking power, work done and time?

Answer 13

power = work done / time

Question 14

What is conduction?

Answer 14

The process where vibrating particles transfer energy to surrounding particles and occurs mostly in solids.

Question 15

What is convection?

Answer 15

The process where energetic particles move away from hotter to cooler regions in fluids.

Question 17

How does a convection current caused by a radiator work?

Answer 17

1. Energy is transferred to nearby particles by conduction
2. The air by the radiator becomes warmer and less dense
3. Warm air rises and is replaced by cooler air which will undergo the same process
4. The warm air transfers energy to the walls and ceilings, losing energy, becoming denser and sinking to be heated by the radiator again.

Question 18

What is the equation for efficiency relating to energy?

Answer 18

efficiency = useful output energy transfer / total input energy transfer

Question 18

How can energy/heat loss be prevented in houses?

Answer 18

Cavity walls to prevent conduction and cavity wall insulation to prevent convection, loft insulation, double glazed windows, draught excluders

Question 18

What is the equation for efficiency relating to power?

Answer 18

efficiency = useful power output / total power input

Question 18

Describe the thermal insulators required practical

Answer 18

1. Boil water in a kettle and pour into a beaker with a lid, measuring the mass
2. Record the initial temperature
3. Time five minutes using a stopwatch and record the final temperature
   4, Pour away the water and allow the container to cool
   repeat the experiment with different materials wrapped around the beaker as insulators

Question 19

What are the finite energy sources?

Answer 19

coal, oil, natural gas (fossil fuels) and nuclear fuel

Question 20

How are fossil fuels formed?

Answer 20

Formed by prehistoric plants and animals buried under layers of rock under high pressure and heat, forming fuels.

Question 21

What are the renewable energy sources?

Answer 21

solar, wind, water waves, hydroelectric, bio-fuel, tidal and geothermal

Question 22

What are the advantages and disadvantages of wind power?

Answer 22

Pros: Renewable, no carbon emissions, minimal running costs Cons: unsightly, noisy, high initial costs

Question 23

What are the advantages and disadvantages of solar power?

Answer 23

Pros: No carbon emissions, free energy, extremely low running costs Cons: high initial costs, small scale, less effective in cloudy countries and at night

Question 24

What are the advantages and disadvantages of geothermal power?

Answer 24

Pros: little environmental damage, reliable, free energy Cons: Only effective in volcanic areas, expensive to build a power plant

Question 25

What are the advantages and disadvantages of hydro-electric power?

Answer 25

Pros: provides an immediate response to energy demand, reliable in droughts, minimal running costs Cons: high initial costs, environmental impact and loss of habitat

Question 26

What are the advantages and disadvantages of wave power?

Answer 26

Pros: no pollution, useful on small islands, minimal running costs Cons: unreliable, disturbing the seabed and habitats, unsightly

Question 27

What are the advantages and disadvantages of tidal barrages?

Answer 27

Pros: can generate a significant amount of energy, fairly reliable, no pollution Cons: preventing boat access, unsightly, altering the habitat

Question 28

What are the advantages and disadvantages of fossil fuels?

Answer 28

Pros: cheap, reliable Cons: finite and releases carbon dioxide

Question 28

What are the advantages and disadvantages of biofuel?

Answer 28

Pros: reliable Cons: high cost to refine, releases carbon dioxide and methane emissions, cannot respond to immediate energy demand

Question 29

What are the advantages and disadvantages of nuclear energy?

Answer 29

Pros: reliable, powerful and relatively cheap Cons: radioactive waste is harmful to the environment when dumped, risk of radioactive disaster

Question 30

What environmental problems are caused by fossil fuels?

Answer 30

Greenhouse effect leading to global warming, sulphur dioxide release causes acid rain, oil spillages