Chapter 4: Energy
Date:____________
Section 1: The Nature of Energy - Notes
Learning Goals:
 Distinguish between kinetic and potential energy.
 Calculate kinetic and gravitational potential energy.
 Describe different forms of potential energy.
What is Energy?:
 Changes are _________________________________________________ in the world.
o

Examples: light bulbs heating the air, sunlight on window, you breathing
Every change requires ______________________.
o
Energy: ______________________________________________________________________
Forms of Energy:
 Electromagnetic energy: energy that __________________________________________________
o

Mechanical energy: energy in ________________________________________________________
o

Example:
Electrical energy: energy carried by ___________________________________________________
o

Example:
Example:
Thermal energy: energy related to ___________________________________________________
o
Example:
Units of Energy:

______________________ – SI unit of energy

Other units:
o
o
o
Kilowatt Hour (kWh)
Kinetic Energy:

Kinetic Energy: the energy that a _________________ object has because of its __________________.
o
Depends on the _____________ and ______________ of the object.


KE =
o
KE =
o
m=
o
v=
Examples:
o A jogger with the mass of 60 kg is moving at a speed of 3 m/s. What is the jogger’s kinetic
energy?
o
A sprinter has a mass of 80.0 kg and a kinetic energy of 4,000 J. What is the sprinter’s speed?
o
A baseball is moving at a speed of 40 m/s and has 120 J of kinetic energy. What is the mass of
the baseball?
Potential Energy:

Potential Energy: __________________ energy due to an object’s _____________________.
o
Three types:




Elastic Potential Energy: energy stored by something that can ______________ or ________________
o

Chemical Potential Energy: energy stored in _______________________________
o

Ex:
Ex:
Gravitational Potential Energy: energy stored in objects due to their ___________________________
_______________ the Earth’s surface
o
Ex:


GPE =
o
GPE =
o
m=
o
g=
o
h=
Examples:
o What is the gravitational potential energy of a ceiling fan that has a mass of 7 kg and is 4 m
above the ground?
o
How high above the ground is a baseball with a mass of 0.15 kg and a GPE of 73.5 J?
o
A rock climber is 200 m above the ground and has a GPE of 117,600 J. What is the rock
climber’s mass?
Changing Energy:

If all of the object on the shelves have the same mass:
o Which has the most potential energy?
o
Which will be moving faster if they were to all fall?

As an object begins to fall, it has both _________ and _________.

As the object gets closer to the ground, it has less ________ and more _______.

Example: An 80 kg diver jumps from a 10 m platform.
o
What is the GPE of the diver at the top of the platform?
o
What is the GPE of the diver after falling 5 m?