Energy stores and systems

Energy AQA GCSE Physics 4.1.1.1

What is the physics definition of a "system"?

An object or a group of objects.

List the 8 main energy stores.

Kinetic, gravitational potential, chemical, elastic potential, magnetic, electrostatic, nuclear, and thermal (internal).

Name three common objects or materials that contain energy in a chemical store.

Food, fuels (such as petrol or coal), and batteries (cells).

Which energy store is associated with moving objects?

The kinetic energy store.

In a bow-and-arrow system, when the bowstring is fully stretched back, in which energy store is energy found?

The elastic potential energy store.

A book is lifted from the floor to a high shelf. Which energy store increases as it moves upwards?

The gravitational potential energy store.

What are the four main pathways by which energy can be transferred between stores?

Mechanically (by a force), electrically (by a current), by heating, and by radiation (such as light or sound).

"Mechanical work" is done when a _______ moves an object through a distance.

Force.

When a current flows through a light bulb, energy is transferred from the chemical store of the battery to the thermal store of the bulb. What is the transfer pathway?

Electrically, by electrical work.

Describe the energy transfer as a ball leaves your hand and travels upwards into the air.

Energy is transferred from the kinetic energy store of the ball to its gravitational potential energy store as it gains height.

A moving car hits a wall and stops. The car’s kinetic energy decreases. Where is most of this energy transferred to?

To the thermal energy stores of the car, wall, and surroundings, and to the surroundings by sound.

In an electric kettle, energy is transferred electrically to the heating element. It is then transferred by ______ to the thermal store of the water.

Heating.

When a vehicle slows down, friction acts between the brake pads and wheels. Describe the energy transfer.

Energy is transferred mechanically from the kinetic energy store of the vehicle to the thermal energy store of the brakes and surroundings.

State the Law of Conservation of Energy.

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

What is a "closed system" in physics?

A system where no energy or matter enters or leaves, so the total energy of the system remains constant.

At the highest point of a pendulum’s swing, which energy store is at its maximum?

The gravitational potential energy store.

As a pendulum swings from the highest point to the lowest point, energy is transferred from the gravitational potential energy store to the _______ store.

Kinetic energy store.

What does it mean when energy is "dissipated"?

Energy is spread out into the surroundings, often as thermal energy, and becomes less useful.

An old filament lamp transfers some energy usefully as light. What is the main form of wasted (dissipated) energy?

Thermal energy (heat) transferred to the surroundings.

Friction in a machine causes unwanted energy transfer to the thermal store. What can be added to the moving parts to reduce this?

Lubrication, such as oil or grease.