Energy

Question 1

Name four energy stores.

Answer 1

Thermal, kinetic, grav. potential, elastic potential, chemical, magnetic, electrostatic, nuclear

Question 2

Describe the energy transfers that occur as a ball falls to the ground.

Answer 2

The ball is accelerated by gravity - the gravitational force does work. It causes energy to be transferred from the ball’s grav. potential store to its kinetic energy store.

Question 3

Give the equation for finding the energy in an object’s kinetic energy store.

Answer 3

Kinetic Energy = 1/2 x mass x (speed)²

Question 4

If energy is transferred to an object’s kinetic energy store, what happens to its speed?

Answer 4

It will increase.

Question 5

Give the equation for finding the energy in an object’s gravitational potential energy store.

Answer 5

GPE = mass x gravitational field strength x height

Question 6

What kind of energy store is energy transferred to when you compress a spring?

Answer 6

Elastic potential.

Question 7

What is the definition of the specific heat capacity of a material?

Answer 7

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

Question 8

Give the equation that relates energy transferred and specific heat capacity,

Answer 8

Change in thermal energy = mass x specific heat capacity x temperature change

Question 9

State the conservation of energy principle.

Answer 9

Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed.

Question 10

Define power.

Answer 10

The rate of energy transfer, or the rate of doing work.

Question 11

Give two equations to calculate power.

Answer 11

Power = energy transferred / time
Power = work done / time

Question 12

What are the units of power?

Answer 12

Watts

Question 13

How can you reduce unwanted energy transfers in a machine with moving, touching components?

Answer 13

Lubrication

Question 14

True or false? A high thermal conductivity means there is a higher rate of energy transfer.

Answer 14

True

Question 15

Give four ways to prevent unwanted energy transfers in a home.

Answer 15

Loft insulation
Double-glazed windows
Draught excluders
Cavity walls

Question 16

True or false? Thicker walls make a house cool down quicker.

Answer 16

False

Question 17

What is the efficiency of an energy transfer?

Answer 17

The percentage of energy input that is actually useful.

Question 18

Give the equation that relates efficiency to power.

Answer 18

Efficiency = useful power input / total power input

Question 19

Name four renewable energy resources.

Answer 19

The sun, wind, water waves, hydro-electricity, bio-fuel, tides, geothermal

Question 20

Name three non-renewable energy resources.

Answer 20

Coal, oil, natural gas

Question 21

What is the difference between renewable and non-renewable energy resources?

Answer 21

Renewable energy resources will never run out, but non-renewable resources will run out eventually.

Question 22

Give an example of how a renewable energy resource is used in everyday life.

Answer 22

Vehicles that run on bio-fuels

Question 23

Explain why solar power is considered to be a fairly reliable energy resource.

Answer 23

In sunny areas where there’s not much variation in the weather, solar panels are reliable in supplying power during the sunlight hours.

Question 24

Give two ways in which the environment can be damaged when using fossil fuels.

Answer 24

Fossil fuels release CO2 into the atmosphere, which contributes to global warming.
Burning coal and oil releases sulphur dioxide into the atmosphere, which causes acid rain.