Dr Pusey

Energy makes things happen

An object is said to have energy if it can cause some change to occur

“Energy is the ability to do work”

Energy is conserved – it cannot be created or destroyed

Energy is measured in Joules (J)

Energy comes in different forms including:

gravitational potential

electrical potential

elastic potential

chemical potential

kinetic

heat

sound

light

Mechanical energy is the energy types specifically related to motion

In this topic we are interested in:

gravitational potential energy (sometimes just called potential energy, PE or EP)

kinetic energy (KE, EK)

Potential energy = stored energy

A result of an object’s position

Potential energy = stored energy

A result of an object’s position

Example 1

What potential energy does a 1 tonne wrecked car gain when a crane lifts it off the ground and puts it on top of a 3 m high pile of scrap?

Example 1

What potential energy does a 1 tonne wrecked car gain when a crane lifts it off the ground and puts it on top of a 3 m high pile of scrap?

Kinetic energy = moving energy

If an object is moving it has kinetic energy

Kinetic energy = moving energy

If an object is moving it has kinetic energy

Kinetic Energy (J)

Velocity (m/s)

Mass (kg)

Example 2

What is the kinetic energy of a 42 kg skateboard rider who has a velocity of 3.7 m/s East?

Example 2

What is the kinetic energy of a 42 kg skateboard rider who has a velocity of 3.7 m/s East?

The meaning of the word ‘work’ in physics is different from everyday use

Work is the energy change in an object, it can be calculated by using the following:

The meaning of the word ‘work’ in physics is different from everyday use

Work is the energy change in an object, it can be calculated by using the following:

Work (J)

Displacement (m)

Force (N)

Example 3

How much work is done if you apply a 200 N force to move a book case 4 m?

Example 3

How much work is done if you apply a 200 N force to move a book case 4 m?