yr10 - energy and work

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?