Topic 1- Energy

Question 1

Define specific heat capacity of a substance

Answer 1

the amount of energy needed to raise the temperature of 1 kilogram of a substance by 1 celsius

Question 2

What is the definition for power

Answer 2

the rate at which energy is transferred

Question 3

Describe the energy changes when a ball is thrown upwards

Answer 3

• upwards- chemical energy in the muscles convert to ke converted to gpe
• peak- maximum gpe, zero ke
• downwards- gpe is converted to ke

Question 4

Describe energy changes for a bunjee jumper

Answer 4

• falling- gpe converte to ke
• as cord tightens , ke is converted and stored as gpe
• lowest point- jumpers initial gpe equals elastic potential energy stored in rope.

Question 5

examples of chemical energy stores

Answer 5

• food
• fuel
• batteries

Question 6

State the law of energy conservation

Answer 6

energy cannot be created or destroyed, only transferred into different forms

Question 7

State any changes in the total energy of a ball that is kicked, assuming that no external forces act.

Answer 7

the total energy of the system remains constant due to the conservation of energy

Question 8

What is waste energy?

Answer 8

energy that is not used by the device for its desire purpose

Question 9

Describe the energy changes that occur in a filament light-bulb

Answer 9

• electric energy is transferred into light and heat energy

- light is a useful energy form, heat is wasted

Question 10

How can the efficiency of a system be increased?-

Answer 10

• reducing waste output (lubrication, thermal insulation)

- recycling waste output (recycling thermal output energy as input energy)

Question 11

state the consequences for energy transfer of a material with a high thermal conductivity.

Answer 11

the rate of energy transferred through the material is higher than for the material with a lower thermal conductivity

Question 12

do double-glazed windows have a higher or lower thermal conductivity than single-glazed windows?

Answer 12

lower, meaning less energy transfers through them

Question 13

what factors affect the rate of cooling for a building?

Answer 13

• thickness of walls

- thermal conductivity of walls

Question 14

methods of reducing heat loss in a building

Answer 14

• double glazing
• loft and wall insulation
• thicker walls

Question 15

What is a renewable energy source?

Answer 15

an energy source which can be replenished as its used up

Question 16

4 examples of renewable energy sources

Answer 16

• wind
• hydro
• solar
• tidal

Question 17

advantages of using gas instead of coal

Answer 17

• flexible generation: gas power stations have short start-up times so it can be switched on and off more readily
• lower emmissions of co2

Question 18

disadvantages of using renewable energy resources

Answer 18

• output controlled by external factors so supply uncertain

- more economic and efficient benefit using non-renewable

Question 19

advantages of fossil fuels

Answer 19

• reliable
• cost effective
• large amount of energy produced

Question 20

advantages of nuclear power

Answer 20

• very large amounts of energy for relatively small amounts of fuel
• doesnts release greenhouse gases
• low fuel costs

Question 21

disadvantages of nuclear power

Answer 21

• produces nuclear waste harming humans and must be stored safely
• non-renewable
• risk of nuclear accidents fatal for humans and envionments

Question 22

how does hydroelectic power produce energy?

Answer 22

• rainwater collects behind a dam
• when this water is released, it is used to turn a turbine
• turbine turns a generator which produces electricity

Question 23

disadvantages of using biofuels

Answer 23

• plants burned or decay, release co2
• in order to grow biofuels, need to destroy land
• growing biofuels reduces land for crops

Question 24

advantages of using tidal energy

Answer 24

• no greenhouse gases produced
• reliable as tides happen twice a day
• cheap as tides are natural

Question 25

advantages of solar panels

Answer 25

-renewable
remote areas where some energy isnt ccessible
-dont cause harm to environment

Question 26

What are the units for specific heat capacity?

Answer 26

J/kg *C