Energy

Question 1

What is a system

Answer 1

An object or group of objects

Question 2

What is the equation for kinetic energy

Answer 2

0.5 x mass x speed(squared)

Question 3

What is the equation for elastic potential energy

Answer 3

0.5 x spring constant x extension (squared)

Question 4

What is the equation for gravitational potential energy

Answer 4

Mass x gravitational field strength x height

Question 5

What are examples of energy stores

Answer 5

Kinetic energy store
Gravitational potential store
Chemical store
Elastic potential store
Nuclear store
Internal store

Question 6

What is specific heat capacity

Answer 6

The amount of energy needed to raise the temperature of 1 kilogram of a substance by 1 degree Celsius

Question 7

What happens if you increase an objects temperature

Answer 7

Increases the energy in the kinetic store of the bodies particles meaning that the energy in the objects internal store also increase

Question 8

What is the law of conservation

Answer 8

Energy cannot be created or destroyed. Instead it can only be transferred

Question 9

What happens with mechanical work

Answer 9

Energy transferred from 1 object to another via a force is an example of mechanical work

Question 10

What happens with electrical work

Answer 10

An electrical current transfers energy from one object to another like a battery powering a torch

Question 11

What are the energy changes when a ball is thrown upwards

Answer 11

Upwards-KE is converted into GPE
peak-maximum GPE zero KE
Downwards- GPE converted to KE

Question 12

What are the energy transfers for a bungee jumper

Answer 12

When falling-GPE converted to KE
As cord tightens KE converted to EPE
lowest point- jumpers initial GPE equals the EPE stored in the cord

Question 13

Why does a bungee jumper slow down once the chord begins to stretch

Answer 13

Kinetic energy decreases since it is converted to elastic potential energy
Since kinetic energy is proportional to velocity (squared) as kinetic energy decreases so does the velocity

Question 14

What happens if more work is done

Answer 14

Push with the same force for a longer distance or push with a larger force for the same distance

Question 15

What is the equation for work done

Answer 15

Work done = force x distance

Question 16

What is the definition of power

Answer 16

The rate at which energy is transferred

Question 17

What are the two equations for power

Answer 17

Power=energy transferred over time
Power=work done over time

Question 18

Two mothers lift the same mass through the same height. Motor A does this in half the time of Motor B. Which dissipates the most power?

Answer 18

Motor A. The energy transferred is the same but the time taken is less

Question 19

What are examples of chemical energy stores

Answer 19

Food
Fuel
Batteries

Question 20

What is waste energy

Answer 20

The energy that is not used by the device for its desired purpose

Question 21

What is an example of wasted energy

Answer 21

Friction- in almost encrypted energy transfer friction creates heat energy and this energy is wasted

Question 22

Describe the energy changes that occur in a filament light bulb

Answer 22

Electrical energy is transferred into light and heat energy
Light in a useful energy form however heat is waste energy

Question 23

How can you calculate efficiency of energy transfers

Answer 23

Useful output energy transfer/Total input energy transfer
Useful power output/total power output

Question 24

How can the efficiency of a system be increased

Answer 24

Reducing waste output
Recycling waste output

Question 25

What is a consequence for energy transfer of a material with a high thermal conductivity

Answer 25

Rate of energy transfer through the material is higher than for a material with a lower thermal conductivity

Question 26

How can you reduce unwanted energy

Answer 26

Lubrication-can reduce the friction between surfaces of objects causing some energy to be dissipated Thermal insulation-as heat will be lost through roof windows walls and floors

Question 27

How can the efficiency of a radiator be improved

Answer 27

Installing metal foil sheets behind the radiator to reflect the Heat back into the room rather than it being absorbed into the walls

Question 28

How can the efficiency of boiling water in a pan be improved

Answer 28

By placing a lid on the pan to reduce the heat loss from the top

Question 29

What is a renewable energy resource

Answer 29

An Energy source which can be replenished as it’s being used up

Question 30

What are the example of renewable resources

Answer 30

Wind Geothermal Hydroelectric Tidal Solar

Question 31

What is an example of a non renewable energy resource

Answer 31

Fossil fuels like coal oil or gas

Question 32

What are the disadvantages to using renewable energy

Answer 32

Often determined by external factors like wind speed so supply is uncertain Generating power through other means is often more efficient and economically beneficial

Question 33

What are the environmental impacts of burning fossil fuels

Answer 33

Carbon dioxide contributed to the greenhouse effect and caused global warming Supper dioxide leads to acid rain which can damage buildings and crops

Question 34

What are the advantages of fossil fuels as an energy resource

Answer 34

Reliable- not dependant on external factors Can produce large amounts of energy for a given quantity Still relatively abundant so cost effectivr Used for more large scale energy supplies due to large energy output per kg of fuel

Question 35

What are the advantages of solar panels

Answer 35

Don’t harm the environment Renewable Can be used in remote areas

Question 36

How has the uk increased renewable energy

Answer 36

Government policy-governments are introducing targets for renewable energy Power plants- energy providers are building power plants that use renewable resources Vehicles-vehicle makers are creating electric use Renewable energy has become more important due to the finite lifetime of fossil fuels

Question 37

What are the limits of renewable energy

Answer 37

Cost-expensive to build power plants Reliability-less reliable than fossil fuels Politics-may not be keen on renewable

Question 38

What is the method for determining specific heat capacity

Answer 38

1)set up your equipment ensuring to wrap insulation around the base and sides of the block. 2) if the thermometer has an air gap surrounding it when placed into the second hole, drop water into the hole using a pippette to increase thermal contact

Question 39

Method for specific heat capacity (2)

Answer 39

3) if the power of the heater is unknown switch on the power supply and measure the current and potential Calculate the power using Power=current x potential difference 4) keep the power supply on and start the timer. Measure the temperature of the block every 10 minutes

Question 40

Specific heat capacity method (3)

Answer 40

5) plot a graph of temperature against work done by the heater. Calculate the gradient of the line 6) specific heat capacity is the gradient divided by the mass of the block. Since the mass is 1 kg the inverse of the gradient is the specific heat capacity of the block

Question 41

What are the main energy uses

Answer 41

Transport Electricity generation Heating

Question 42

What are the patterns and trends of energy use

Answer 42

During industrial revolution fossil fuels became an important source of energy as it was easy to mine and provided lots of energy Only recently had renewable energy become more suitable- technology has ad to develop a lot to harness such energy sources efficiently Easier to use energy resources due to increasing pressure to cope with the publics power demands but harder to solve environmental issue due to political social ethical and economic considerations