Science - Energy

What is energy?

The ability to cause change or do work.

What is the unit of energy?

The joule (J).

What is kinetic energy?

Energy an object has because of its movement.

What is potential energy?

Stored energy that an object has because of its position, shape or condition.

Give an example of kinetic energy.

A moving car, rolling ball or running person.

Give an example of gravitational potential energy.

A book sitting on a high shelf.

What happens to gravitational potential energy when an object gets higher?

It increases.

What happens to kinetic energy when an object moves faster?

It increases.

What is the law of conservation of energy?

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

What is an energy transfer?

Energy moving from one object or place to another.

What is an energy transformation?

Energy changing from one form to another.

What energy transformation occurs in a torch?

Chemical → electrical → light + thermal.

What energy transformation occurs in a moving car?

Chemical → kinetic + thermal + sound.

What is thermal energy?

Energy associated with the movement of particles in matter.

What is chemical energy?

Energy stored in chemical substances, such as food and fuels.

What is electrical energy?

Energy associated with the movement of electric charges.

What is light/radiant energy?

Energy carried by electromagnetic waves, such as visible light.

What is sound energy?

Energy transferred through vibrations and waves.

What is renewable energy?

Energy from sources that are naturally replenished.

Give three renewable energy sources.

Solar, wind and hydroelectric energy.

What is non-renewable energy?

Energy from sources that are limited and take extremely long periods to form.

Give three non-renewable energy sources.

Coal, oil and natural gas.

How does a solar panel generate electricity?

It converts energy from sunlight into electrical energy.

How does a wind turbine generate electricity?

Moving air turns the blades, which drive a generator.

How does a hydroelectric power station generate electricity?

Moving water turns turbines connected to generators.

What is efficiency?

How much of the input energy is converted into useful output energy.

Why are machines never 100% efficient?

Some energy is transferred into unwanted forms, usually thermal energy and sound.

What is friction?

A force that opposes motion between surfaces.

What usually happens to energy when friction acts?

Some useful energy is transformed into thermal energy.

What is a force?

A push or pull that can change an object's motion.

What is work in physics?

Work is done when a force causes an object to move through a distance.

What is power?

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

What is the unit of power?

The watt (W).

What does a higher-power appliance do?

It transfers energy faster.

What is an energy-efficient appliance?

An appliance that produces more useful output for the energy it uses.