Energy

What does energy mean in science?

Energy is the capacity to do work or produce change.

What are the types of potential energy?

Chemical, gravitational, magnetic, nuclear, elastic, and electrical potential energy

What are the types of active energy?

Heat, kinetic, light, and sound

What are chemical, gravitational and elastic potential energy?

Chemical: stored in chemicals.
Gravitational: due to height.
Elastic: stored when stretched or compressed.

What are the four types of active energy and what do they mean?

Heat: thermal energy.
Sound: energy carried by sound waves.
Light: energy carried by light.
Kinetic: energy of movement.

What is the law of conservation of energy?

Energy cannot be created or destroyed, only transferred or transformed.

What is energy efficiency?

The percentage of input energy converted into useful output energy.

How do you calculate efficiency?

Efficiency = (useful output energy ÷ total input energy) × 100%.

What is wasted energy?

Energy that is not useful, often transferred as heat or sound.

Why do different chemicals store different amounts of energy?

They contain different types and numbers of atoms.

Why do materials expand when heated?

Their particles gain kinetic energy, vibrate faster and move further apart.

What is a bimetallic strip?

Two different metals joined together that bend when heated because they expand at different rates.

What are three problems caused by expansion and contraction?

Structures can buckle, bridges need expansion gaps, and wires change length.

What are the three methods of heat transfer?

Conduction, convection and radiation.

What is conduction?

Heat transfer through interactions between neighbouring particles, especially in solids.

What is convection?

Heat transfer in liquids and gases as warm, less dense fluid rises and cooler, denser fluid sinks.

What is radiation?

Energy transfer by electromagnetic waves; it does not need a medium.

What is the difference between conduction and convection?

Conduction transfers energy through particle interactions; convection transfers energy through moving fluids.

How do dark and light surfaces absorb thermal radiation?

Dark surfaces absorb more thermal radiation; light surfaces absorb less.

How can electricity be generated using magnets?

By moving a wire through a magnetic field or moving a magnetic field relative to a wire.

What are three ways to generate electricity?

Wind turbines, solar panels and hydroelectric dams.

How do you calculate gravitational potential energy (GPE)?

GPE = mass × gravity × height (\(mgh\)). It is measured in joules (J).

What happens to GPE if mass or height doubles?

GPE doubles if either mass or height doubles while the other stays constant.

What happens to particles when a material is heated?

They gain kinetic energy and vibrate or move faster.

What are electrical, magnetic, and nuclear energy and what do they mean?

Electrical: associated with electric charges.
Magnetic: stored in a magnetic field.
Nuclear: stored in an atom’s nucleus.

How can heat loss be measured?

Measure the temperature change over time using a thermometer.