1. Unit 3
Energy, Work and Power

2. In this unit, you will be able to:
Define and describe concepts related to energy – i.e. types of energy
Demonstrate an understanding of energy transformations and how this relates to efficiency
Define and describe the physics concepts of work and power and how it relates to energy
Demonstrate an understanding of changes of state and how latent heat is involved
Analyze the costs and benefits of various energy sources and energy transformation technologies that are used around the world

3. The Kinds and Forms of Energy
Energy is the ability to do work
energy is transferred from one object to another whenever work is done
energy is always conserved in a closed system
energy can be transferred , changed from one form to another, or stored
all energy forms eventually become waste heat

4. Forms of Energy
gravitational potential energy
potential energy an object has as a result of its distance above a reference point
i.e. raising a hammer
elastic potential
energy stored in an object when its is forced out of shape
i.e. sling shot
nuclear potential
energy stored in the nucleus of an atom
i.e. nuclear fision
chemical potential
energy stored in molecules
i.e. food
kinetic
energy of motion
i.e. riding a bike

5. thermal
energy an object has as a result of the random motion of molecules
i.e. boiling water
sound
energy that is carried from molecule to molecule by vibrations
i.e. thunder
radiant
energy that travels as electromagnetic waves
i.e. the sun
electrical
energy associated with moving electric charges
i.e. lightning

6. Energy Transformations
Recall that energy can change from one form to another.
i.e. the sun heating a solar powered car
sound
energy
radiant
energy
chemical
potential
electric
energy
kinetic
energy
heat
(friction)
More Examples of Energy Transformations
Waterslide 1
Waterslide 2
Myth Busters
Honda – Rube Goldberg
Iphone Rube Goldberg
Insane Domino Tricks

7. Measuring Energy
energy is measured by determining the work done or the heat produced
whenever work is done, energy is used
more energy is always consumed than the work accomplished
this is because friction is always present and the energy used to overcome friction becomes waste heat
joule (J)
kilojoule (kJ) = J (103)
megajoule (MJ) = (106)
gigajoule (GJ) = (109)
4.1 Prac. #2,3
UC #1,2