Energy Changes

Question 1

What is the equation for kinetic energy?

Answer 1

1⁄2 x Mass x (Velocity)^2

Question 2

What is the equation for elastic potential energy?

Answer 2

1⁄2 x Spring Constant x (Extension)^2

Question 3

What is the equation for gravitational potential energy?

Answer 3

Mass x Gravitational Field Strength x Height

Question 4

What is the ‘Specific Heat Capacity’ of a substance?

Answer 4

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

Question 5

State the units for Specific Heat Capacity.

Answer 5

J/°C/kg

Question 6

What is the definition of ‘Power’?

Answer 6

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

Question 7

State two equations for power.

Answer 7

power = energy transferred/time
power = work done/time

Question 8

What is the unit of power?

Answer 8

Watt (W)

Question 9

State 4 different stores of energy.

Answer 9

1. Kinetic Energy
2. Gravitational Potential Energy
3. Elastic Potential Energy
4. Chemical Energy

Question 10

State the law of energy conservation

Answer 10

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

Question 11

What is waste energy?

Answer 11

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

Question 12

State two equations to calculate efficiency.

Answer 12

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

Question 13

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

Answer 13

Lower, meaning less energy transfers through them.

Question 14

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

Answer 14

The thickness of the walls
The thermal conductivity of the walls

Question 15

State three methods of reducing heat loss in a building.

Answer 15

Double glazing
Loft and wall insulation
Thicker walls

Question 16

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

Answer 16

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

Question 17

What is a renewable energy resource?

Answer 17

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

Question 18

Give four examples of renewable energy resources.

Answer 18

1. Wind Energy
2. Hydro-Electricity
3. Tidal Energy
4. Solar Energy

Question 19

Give an example of a non-renewable energy resource

Answer 19

Fossil fuels (for example coal, oil and gas).

Question 20

State two disadvantages of using renewable energy resources to generate power

Answer 20

Output 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 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

State three advantages of fossil fuels as an energy resource

Answer 22

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 23

State three advantages of nuclear power.

Answer 23

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

Question 23

What are some disadvantages of using biofuels?

Answer 23

●When plants are burned or decay they release CO2
●In order to grow biofuels, you need to destroy land destroying natural habitats

Question 24

How does hydroelectric power produce energy?

Answer 24

● 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 25

What are the advantages of tidal energy sources?

Answer 25

● 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 26

What are the disadvantages of hydroelectric power?

Answer 26

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

Question 27

What are some advantages of solar panels?

Answer 27

● 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