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Energy
Mr. Skirbst
What is energy?
What is energy?
- It is the ability to do work or
cause change
(remember: work = force x distance)
Unit of energy = Joule
5 FORMS of Energy
5 FORMS of Energy
1. Mechanical
- “matter in motion”
- (ex. ball, bike, run, blood)
5 FORMS of Energy
2. Heat
- “atomic motion”
- (ex. melting, evaporation)
5 FORMS of Energy
3. Chemical
- “atomic bonding”
- (ex. burning, reactions)
5 FORMS of Energy
4. Electromagnetic
- “moving electrons”
- (ex. electricity, lights,
motors)
5 FORMS of Energy
5. Nuclear
- “fusion / fission”
- (ex. stars, atomic bomb)
2 STATES of Energy
2 STATES of Energy
1. Kinetic
(Greek – “kinetikos” motion)
- energy of motion
2 STATES of Energy
* depends upon mass & velocity
K.E. = (mv2) / 2
m = mass; v = velocity
2 STATES of Energy
2. Potential
- energy of position
* stored energy (ex. food,
fuel, suspended objects)
2 STATES of Energy
“The bigger they are,
the harder they fall”
P.E. = mgh
m = mass; g = gravity; h = height
Energy Conversions
Energy can be transferred
from one object to another
& from one form to another
Energy Conversions
Energy Conversions
KE = ½
2
mv
medium
slow
0
0
Velocity
fast
GRAPH
light
Mass
medium
heavy
Example Problems
m = 2 kg; v = 2 m/sec
What is the KE?
Example problem
A 6 kg bowling ball is thrown with a velocity
of 4m/sec. Calculate its kinetic energy.
Example problem
A 5,000 kg car hits a deer with a velocity of
10m/sec. Calculate its kinetic energy. What
will happen to the deer?
Activity 1 - Bowling Ball:
Level 1: Bowling Ball – Find the Kinetic Energy
Hint: You will need a ruler, stopwatch, and calculator to complete this. Also, remember that:
velocity(m/sec) = distance(m) / time(sec)
d = 10 m
t=
v=
draw
TOV
m=
v=
KE =
equation
2
KE = ½ mv
PIV
solution
Level 2: Bowling Ball – Find the Potential Energy of the ball held at 1 meter above the floor.
Don’t forget to use the spring balance to find the mass in kg.
draw
TOV
equation
PIV
solution
Level 3: Bowling Ball – How high would the bowling ball have to be to have a PE equal to the
KE from level 1? (Hint: use algebra to solve for the height; PE=mgh)
Level 3: Bowling Ball – How high would the bowling ball have to be to have a PE equal to the
KE from level 1? (Hint: use algebra to solve for the height; PE=mgh)