Energy

Question 1

What is chemical energy?

Answer 1

Potential energy stored in chemical bonds of molecules

Question 2

What is elastic potential energy?

Answer 2

The potential energy associated with objects that can be stretched or compressed

Question 3

What is electromagnetic energy?

Answer 3

A form of energy that travels through space as waves

Question 4

What is gravitational potential energy?

Answer 4

Potential energy that depends upon an objects height

Question 5

What is kinetic energy?

Answer 5

The energy an object has due to its motion

Question 6

What is nuclear energy?

Answer 6

The potential energy stored in the nucleus of an atom

Question 7

What is thermal energy?

Answer 7

The total kinetic and potential energy of all the particles in a substance

Question 8

What is mechanical energy?

Answer 8

Kinetic or potential energy associated with the motion or position of an object

Question 9

Define specific heat capacity

Answer 9

The amount of energy needed to raise the temperature of 1kg of a substance by 1 degrees

Question 10

What is the definition of power?

Answer 10

The rate of which energy is transferred (or rate at which work is done)

Question 11

Two motors 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 11

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

Question 12

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

Answer 12

Upwards: KE is converted into GPE
Peak: maximum GPE, zero KE
Downwards: GPE is converted into KE

Question 13

Describe the energy transfers for a bungee jumper

Answer 13

As the cord tightens, KE is converted and stores as elastic potential energy
At lowest point, the jumpers initial GPE equals the EPE stored in the cord

Question 14

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

Answer 14

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

Question 15

Give examples of chemical energy stores

Answer 15

Food
Fuel
Batteries

Question 16

State the law of energy conservation

Answer 16

Energy cannot be created or destroyed (it can only be transferred into different forms)

Question 17

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

Answer 17

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

Question 18

What is waste energy?

Answer 18

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

Question 19

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

Answer 19

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

Question 20

How can the efficiency of a system be increased?

Answer 20

1. Reducing waste output
2. Recycling waste output

Question 21

State the consequence for energy transfer of a material with a high thermal conductivity

Answer 21

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

Question 22

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

Answer 22

Lower, meaning less energy transfers through them

Question 23

What key factors affetc the rate of cooling of a building?

Answer 23

The thickness of the walls
The thermal conductvity of the walls

Question 24

State three methods of reducing heat loss in a building

Answer 24

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

Question 25

How can the efficiency of a mechanical machine with moving parts be improved?

Answer 25

Lubricate any moving parts to reduce the friction and therefore energy loss due to heating

Question 26

How can the efficiency of a radiator be improved?

Answer 26

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

Question 27

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

Answer 27

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

Question 28

What is a renewable energy resource?

Answer 28

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

Question 29

Give four examples of renewable energy resources

Answer 29

Wind energy Hydro-electricity Tidal energy Solar energy

Question 30

Give an example of a non renewable enegry resource

Answer 30

Fossil fuels

Question 31

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

Answer 31

Flexible generation: Gas power stations have short start-up times so can be switched on/off more readily Lower emissions of carbon dioxide

Question 32

State two disadvantages of using renewable energy resources to generate power

Answer 32

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

Question 33

Explain the environmental impacts of burning fossil fuels

Answer 33

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

Question 34

State three advantages of fossil fuels as an energy resource

Answer 34

Reliable: Not dependent on external factors so can generate power anytime Can produce large amounts of energy for a given quantity Still relatively abundant, so cost-effective

Question 35

State three advantages of nuclear power

Answer 35

- Very large amounts of energy for relatively small quantities of fuel - Doesn't release greenhouse gases and so doesn't contribute to climate change - Low fuel costs

Question 36

State three disadvantages of nuclear power

Answer 36

- Produces nuclear waste which is harmful to humans and must be safely stored for centuries - Non-renewable energy source - Risk of nuclear accidents, which have fatal consequences on humans and the environment

Question 37

How does hydroelectric power produce energy?

Answer 37

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

Question 38

What are some disadvantages of using biofuels?

Answer 38

When plants are burned or decay they release CO2 In order to grow biofuels, you need to destroy land Growing biofuels reduces the land available for growing food

Question 39

What are the advantages of tidal energy sources?

Answer 39

- They do not produce greenhouse gases - They are quite reliable, as tides happen twice a day - They are cheap to run as tides are natural, and so are free

Question 40

What are the disadvantages of hydroelectric power?

Answer 40

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

Question 41

What are some advantages of solar panels?

Answer 41

- They don't cause harm to the environment - They are a renewable resource - They can be used in remote areas where other types of energy are less accessible

Question 42

Give an example of a social factor which may act as a deterrent for certain typs of energy pollution

Answer 42

- Visual pollution - Sound pollution