Download Energy and Work - AP Physics 2 Homework Page

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
Velocity (m/s)
Kinetic Energy (J)
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:
Displacement
(m)
Work (J)
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)