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Dr Pusey
Define: energy mechanical energy kinetic energy instantaneous kinetic energy potential energy instantaneous potential energy work
Identify and name the following types of energy: gravitational potential electrical potential elastic potential chemical potential kinetic heat sound light
Give the SI units for energy Use and rearrange the equations for potential energy, kinetic energy to solve problems Analyse real world situations in terms of energy and work (e.g. rollercoasters)
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)
Instantaneous kinetic/potential energy refers to how much kinetic/potential energy an object has at a certain point in time
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?
Example 4
A technician is testing a new safety glass product. She fires an 8x10-2 kg object with a speed of 130 m/s at a sheet of the glass. The glass shatters and the object emerges at 65 m/s. How much work did the object do to shatter the glass?
Example 4
How did you go? Define:
energy mechanical energy kinetic energy instantaneous kinetic energy potential energy instantaneous potential energy work
Identify and name the following types of energy: gravitational potential electrical potential elastic potential chemical potential kinetic heat sound light
Give the SI units for energy Use and rearrange the equations for potential energy, kinetic energy to solve problems Analyse real world situations in terms of energy and work (e.g. rollercoasters)
