Energy Transfers

Question 1

Equation for gravitational potential energy

Answer 1

GPE = mass (kg) x gravitation field strength (N/kg) x height

Question 2

Equation for Kinetic energy

Answer 2

1/2 x mass x (velocity)^2

1/2 x m x v^2

Velocity(m/s)

Question 3

What is meant by conservation of energy

Answer 3

Total amounts of energy in a closed system that remains constant
Energy cannot be made of destroyed by can change from one form to another

Question 4

Describe energy changes involved when a ball is thrown upwards and then returns to starting position

Answer 4

Upwards : KE is converted to GPE
Peak : Maximum GPE, zero KE
Downwards : GPE is converted to KE

Question 5

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

Answer 5

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

Question 6

Describe the energy changes that occur in a filament light bulb

Answer 6

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

Question 7

Describe the energy transfers for a bungee jumper

Answer 7

When falling the GPE is converted to KE of the jumper
As the cord tightens the KE is converted and stored as elastic potential energy (EPE)
At lowest point the jumpers initial GPE equals the EPE stored in the cord

Question 8

Explain why a bungee jumper slows down once the cord begins to stretch

Answer 8

KE decreases since it is converted to elastic potential energy
Since KE is proportional to velocity^2, as KE decreases, so does velocity

Question 9

What is waste energy

Answer 9

Energy that is not used by the device for its desired purpose, or not converted into the desired form

Question 10

Two equations to calculate efficiency

Answer 10

Useful output energy / total input energy

Useful power output / total power output

Question 11

State the consequence for energy transfers of a material with a night thermos conductivity

Answer 11

The rate of energy transfer through the material is higher than for a 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

State three methods of deducting heat loss in a building

Answer 13

1. Double glazing
2. Loft and wall insulation
3. Thicker walls

Question 14

How can you reduce unwanted energy transfer in a mechanical system

Answer 14

Reduce friction by lubricating moving parts

Question 15

How can the efficiency of a system be increased

Answer 15

1. Reducing waste output
2. Recycling waste output

Question 16

What is a renewable energy resource

Answer 16

An energy source which can be replenished as it is being used up

Question 17

Four examples of renewable energy resources

Answer 17

1. Wind energy
2. Hydro electricity
3. Tidal energy
4. Solar energy

Question 18

Example of a non renewable energy resource

Answer 18

Fossil fuels

Question 19

What are the advantages of generating power using gas rather than coal

Answer 19

Flexible generation : gas power stations have short start up times
Lower emission of carbon dioxide

Question 20

Two disadvantages of using renewable energy resources to generate power

Answer 20

Output often determined by external factors so supply is uncertain
Renewable fuel often produce less energy per kg

Question 21

Explain the environmental impacts of burning fossil fuels

Answer 21

Carbon dioxide contributes to the greenhouse effect and causes global warming
Sulphur dioxide leads to acid rain which can damage buildings and crops

Question 22

Three advantages of fossil fuels as an energy resource

Answer 22

Reliable
Produce large amounts of energy per kg
Still relatively abundant so cost effective

Question 23

Three advantages of nuclear power

Answer 23

Very large amounts of energy per kg
No greenhouse gases released
Low fuel costs

Question 24

Three disadvantages of nuclear power

Answer 24

Produces nuclear waste
Non renewable energy source
Risk of nuclear accidents

Question 25

Examples of social factors to consider in energy production

Answer 25

Visual pollution
Sound pollution

Question 26

How does hydroelectric power produce energy

Answer 26

Rainwater collects behind a dam
When this water is released it is used to turn a turbine
This turbine turns a generator which produces electricity

Question 27

Some disadvantages of using biofuels

Answer 27

When plants are burned/decay they release carbon dioxide
In order to grow biofuels you need to destroy land
Growing biofuels reduces the land available for food crops

Question 28

Advantages of tidal energy sources

Answer 28

No greenhouse gases
Fairly reliable as tides occur twice a day
Cheap to run as tides are natural so free

Question 29

Disadvantages of hydro electric power

Answer 29

The dam may cause flooding
It can cost a lot to install the required infrastructure

Question 30

Advantages of solar panels

Answer 30

Don’t cause harm to environment
Renewable resource
Can be used in remote areas where other types of energy are less accessible