Year 8 Science - PHYSICS

What are the 4 types of potential (stored) energy?

• Gravitational

• Elastic

• Chemical

• Nuclear

What are the 5 other types of kinetic energy?

• Kinetic

• Heat

• Thermal

• Sound

• Light

What are waves?

A wave is able to transmit energy from one place to another without moving any matter over this distance.

What are the two types of waves?

• Transverse

• Longitudinal

What is the best known example of longitudinal waves?

sound

Sounds Travel at Different Speeds:

The higher the temperature…

the faster the particles of the medium will move and the faster the particles will carry the sound.

How do we calculate energy efficiency?

useful output energy/total input energy

What are the three ways of energy transfer?

conduction, convection and radiation

In what medium does conduction occur?

in solids

In what medium does convection occur?

in fluids (liquids and gases)

In what medium does radiation occur?

in empty space

What is conduction?

The transfer of heat energy as a result of neighbouring vibrating particles.

What substance has high thermal conductivity?

metals and fluids

What substance has low thermal conductivity?

plastics

What is convection?

The transfer of heat energy by the movement of particles from one region to another in liquids and gases. Cycle of these are called convection currrents.

How do you reduce convection?

By stopping the free flow of fluids.

What is a similarity between conduction and convection?

Both involve particles gaining kinetic energy.

What is radiation?

Heat that is transferred without the presence of particles at all, as electromagnetic radiation. The energy is carried by infrared waves.

Radiation:
The hotter an object is…

the more radiation it emits.

Energy transfers and transformations are never 100% efficient. Some energy isalways wasted in the process of transfer or transformation usually as…

heat energy.

What is a conductor?

A material that allows the flow of electricity through it with very little resistance.

energy

Energy is the ability to do work. It makes things happen. It is need to move or heat something, make noise or outright or to change an objects shape.

Kinetic energy

the energy of movement

Light energy

The energy that warms the planet and allows us to see things more clearly.

Electrical energy

The energy created from the movement of electrons in the electric current.

Thermal (heat) energy

The energy associated with the movement of atoms in a substance. The higher the temperature, the greater the kinetic energy.

Sound energy

The energy associated with vibrations caused by sound passing through a substance.

Potential energy

Energy that is stored and held in readiness

Gravitational energy

The energy of a raised object due to gravity will fall downward. It changes to kinetic energy as the object falls.

Elastic energy

The energy of a stretched or compressed object, which has potential to return to its original shape (e.g. springs or elastics)

Chemical energy

The energy which can be released when a chemical reaction occurs (e.g. inside a battery or fuels) Often heat or light are produced.

How do we measure energy?

Joules (J) or Kilojules (KJ)

1 KJ = 1000 J

What is the law of Conservation

That energy can never be created or destroyed. Energy is conserved or kept as it is converted from one form to another.

what is energy transfer?

Energy transfer is when energy is relocated from one form to another. E.g. Kinetic energy being transferred from a persons foot to the ball.

What is energy transformation?

When energy changed form. E.g Electrical energy turning into sound energy

What is energy efficiency