Topic 4: Energy Resources and Energy Transfers

What are the 6 main energy stores?

Chemical, kinetic, gravitational, elastic, thermal and nuclear.

What is the chemical energy store?

Energy stored in chemical bonds, e.g. in fuels, food and batteries.

What is the kinetic energy store?

Energy stored by an object when it is moving.

What is the gravitational energy store?

Energy stored by an object because of its position in a gravitational field.

What is the elastic energy store?

Energy stored when an object is stretched or compressed.

What is the thermal energy store?

Energy stored due to the random motion of particles within an object.

What is the nuclear energy store?

Energy stored in the nuclei of atoms

What are the four main ways energy can be transferred?

Mechanically, electrically, by heating and by radiation.

What does mechanical energy transfer mean?

Energy is transferred by a force doing work, e.g. lifting or moving an object.

What does electrically mean as an energy transfer?

Energy is transferred by an electric current.

What does energy transfer by heating mean?

Energy is transferred from a hotter object to a cooler object.

What does energy transfer by radiation mean?

Energy is transferred by waves, such as light or sound.

What is the principle of conservation of energy?

Energy cannot be created or destroyed; it can only be transferred between stores.

What does it mean when energy is described as “dissipated”?

Energy is transferred to the surroundings, usually into the thermal store.

What is the equation for efficiency?

Efficiency = useful energy ÷ total energy × 100%

What does 100% efficiency mean?

All the input energy is transferred to the useful output with none wasted.

What is a Sankey diagram used to show?

It shows the energy transfers in a device, including useful and wasted energy.

What does the width of an arrow on a Sankey diagram represent?

The amount of energy being transferred.

What are the three methods of thermal energy transfer?

Conduction, convection and radiation.

How does conduction transfer thermal energy?

Particles transfer energy to neighbouring particles through collisions; metals also transfer energy using free electrons.

How does convection transfer thermal energy?

Warmer, less dense fluid rises and cooler, denser fluid sinks, producing convection currents.

How can thermal energy transfer be reduced in buildings?

Use insulation such as loft insulation and/or double glazed windows