AQA GCSE Physics Energy

An object or a group of objects

A system

What is the energy associated with movement?

Kinetic energy

What type of energy is stored in stretched objects

Elastic potential energy

What type of energy is found in the nuclei of atoms?

Nuclear energy

What type of energy is found in objects raised off the ground?

Gravitational Potential Energy

What type of energy is stored as heat?

Thermal energy

What type of energy is found in bonds between substances?

Chemical energy

What is the equation to work out the kinetic energy of a moving object?

Kinetic energy = 0.5 x mass x speed^2

What is the equation to work out the elastic potential stored in a spring?

Elastic potential energy = 0.5 x spring constant x extension^2

What is the unit for energy?

Joules (J)

What is the equation to work out gravitational potential energy of an object raised off the ground?

G.P.E = mass x gravitational field strength x height

What is mass measured in?

kg

What is speed measured in?

m/s

What is spring constant (Ek) measured in?

N/m

What is extension measured in?

m

If an object started at 5cm long and stretched to 25cm then what would be the value for extension?

0.2m

What is gravitational field strength measured in?

N/kg

How can you calculate the change in thermal energy?

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

What is specific heat capacity?

The amount of energy required to increase the temperature of 1kg of a substance by 1 degree celsius

The rate at which energy is transferred or the rate at which work is done

Power

How do you calculate power using energy transferred?

Power = Energy transferred / time

How do you calculate power using work done?

Power = work done / time

What is power measured in?

Watts (W)

How much energy is transferred each second if the power is 1W?

1J

If you have two motors lifting a weight to the same height but one has more power, then what will be the difference between the rate at which they are lifted?

The higher the power, the faster the object would be lifted.

What is the law of the conservation of energy?

Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed

Wasted energy

What do we call energy that is dissipated?

In a closed system what will happen to the total energy?

There will be no net change in the total energy

How can we reduce the amount of waste energy in a system?

Use lubricants or insulation to reduce energy being wasted as heat

How does thermal conductivity of a material affect the rate of conduction across the material?

The higher the conductivity, the faster the rate of conduction

How does the thickness of a wall affect the rate of cooling of a building?

The thicker the wall, and the lower its conductivity, the slower it will lose heat.

How do you calculate efficiency using energy output?

Efficiency = Useful output energy transfer/total input energy transfer

How do you calculate efficiency using power?

Efficiency = useful power output/total power input

What are the main non-renewable energy resources on Earth?

Fossil fuels (coal, oil and natural gas) and nuclear fuel

What are the main renewable energy resources on Earth?

Bio-fuel, wind, hydroelectric, geothermal, tidal, solar and wave

What are the main uses of energy resources?

Transport, electricity generation and heating

Which energy resource depends on the wind, and is very changeable?

Wind

Which energy resource isn't great in the UK as we don't get much Sun?

Solar

Which energy resource depends on falling water in dams?

Hydroelectric

Which energy resource depends on the movement of water as a result of the pull of the moon?

Tidal

Which energy resource depends on the heat of the Earth?

Geothermal

Which energy resource depends on the sea being rough?

Wave

Which energy resource depends on organic material being burned?

Bio-fuel

Why are renewable resources preferable to non-renewable resources?

They won't run out and do not release greenhouse gases

What is the problem with non-renewable resources?

They will run out

What is the problem with nuclear energy?

It deals with radioactive material and if there is a meltdown then the radioactive environment is uninhabitable

What is the good thing about nuclear energy?

It release huge amounts of energy

What is the problem with fossil fuels?

They are running out and release greenhouse gases such as carbon dioxide. Gases such as sulfur dioxide and nitrogen oxides can also lead to acid rain.

What are the 8 energy stores?

Kinetic

Gravitational potential

Elastic potential

Chemical

Thermal

Nuclear

Electrostatic

Magnetic

What are the 4 energy transfers?

Heating

Radiation - sound and light

Electrically

Mechanically - forces

Energy cannot be created or destroyed. It can only be transferred, stored or dissipated.

The Conservation of Energy Law

How is efficiency presented?

Presented as a ratio - it has no units

When a force moves an object through a distance, energy is transferred.

Work done

How quickly you can transfer energy, or the rate of energy transfer

Since energy transferred and work done are the same, it can also be the rate at which work is done.

Power

P = E/t

Power = Energy transferred / time

Kinetic Energy = 0.5 x mass x velocity squared

KE = 0.5 x m x v^2

Gravitational Potential Energy = mass x gravitational field strength x hieght

GPE = mgh