Download Physics Demonstration

Agenda for 2/17/17
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Potential and Kinetic Energy Notes
Potential and Kinetic Energy Problems
HW – none
Kinetic vs. Potential Energy
Potential Energy
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Potential energy
is STORED energy
due to position.
Ex. A rock on top of
a hill has a potential
to do work.
Kinetic Energy
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Kinetic energy is the
energy that a moving
object has.
Kinetic energy is energy
that depends on MASS and
VELOCITY (movement)
If the rock is allowed to roll
down the hill, then the
potential energy is
converted into kinetic
energy.
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Potential energy is
stored energy—energy
ready to go.
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A lawn mower filled with
gasoline
A car on top of a hill
Students waiting to go
home from school
The light bulb not turned
on
Water stored behind a
dam at a hydroelectric
plant has potential
energy.
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Kinetic energy is energy at
work.
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A lawn mower cutting grass
A car racing down a hill
Students running home from
school
The light energy emitted by
lamps.
Even electrical energy is
kinetic energy.
Whenever we use energy to
do work, it is in the kinetic
state.
Conservation of Energy
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Kinetic Energy could
then be converted
back into potential
energy.
The energy can be
split into Potential
Energy and/or Kinetic
Energy
http://www.youtube.com/
watch?v=Jnj8mc04r9E&fe
ature=related
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As potential energy decreases, the kinetic
energy increases.
As the potential energy increases, the
kinetic energy decreases.
http://www.youtube.com/watch?v=qZ4FF
WvZtyo
Lots of PE no KE 
Equal PE and KE 
No PE maximum
KE right before
he hits bottom 
This also shows
that energy is NOT
being lost, just
changing form!
FORMULAS
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Potential Energy = Mass x Gravity x Height
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Gravity = 9.8 m/s2 (Earth)
Kinetic Energy = ½ Mass x Velocity2
The Units used are:
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Energy = Joules (J)
Height = meters (m)
Mass = kilograms (kg)
Velocity = (m/s)
Examples – Show work on back
of notes
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What is the kinetic energy of a 2,000 kg
boat moving at 5.0 m/s?
K.E. = ½ m x v2
K.E. = ½ (2000) (5)2
K.E. = 25,000 J
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DON’T FORGET YOUR UNITS!
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What is the gravitational potential energy
of a ceiling fan that has a mass of 7 kg
and is 4 m above the ground?
P.E. = mass x gravity x height
P.E. = (7) (9.8) (4)
274 J
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A 1.0-kg ball is thrown into the air with an
initial velocity of 30 m/s.
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a. How much kinetic energy does the ball
have?
K.E = 450 J
b. How much potential energy does the ball
have when it reaches the top at 60 meters
high?
P.E. = 588 J
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Find the height of a baseball with a mass
of 0.15 kg that has a GPE of 73.5 J.
PE = m x g x h
73.5 = 0.15 x 9.8 x h
73.5 = 1.47h
50 m = height
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A jogger whose mass is 60 kg is moving at
a speed of 3 m/s. What is the jogger’s
kinetic energy?
K.E = ½ mv2
K.E. = (0.5) (60) (3)2
K.E. = 270 J
Problem #1
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What is the potential energy of a rock (on
Earth) that has a mass of 100 kg that is
sitting on top of a hill 300 meters high?
294,000 J
Problem #2
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What is the kinetic energy of a bicycle
with a mass of 14 kg traveling at velocity
of 3.0 m/s?
63 J
Problem #3
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A flowerpot with a mass of 500 grams is
sitting on a windowsill 30 meters from the
ground. Is the energy of the flowerpot
potential or kinetic? How many joules in
this?
Potential energy
147 J
Problem #4
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If a bowling ball has a mass of 10kg and is
rolled with a velocity of 15 m/s, what is
the ball’s kinetic energy?
1,125 J
Problem #5
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A boulder is sitting on the top of a
mountain. The boulder has a mass of 500
kg. The mountain is 1500 meters high.
What is the boulder’s potential energy
before it released?
7,350,000 J
Problem #6
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A 1200 kg automobile is traveling at a
velocity of 100 m/s. How much kinetic
energy does it possess?
6,000,000 J
Agenda for 2/23/16
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Go over homework
New lab groups
Kinetic Energy and Potential lab
HW – none
Quiz Thursday!
Lab Groups – Period 4
Station 1 – Griffin, Tyler, Emma, Maddie
Station 2 – Aiden, Nolan, Caleb, Lauren,
Adah
 Station 3 – Alex, Sam Glover, Anna,
Landon, Jack
 Station 4 – Quinn, Reyan, Genevieve,
Ella, Sophia W
 Station 5 – Sam, Connor, Riley, Sophia
B
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Lab Groups – Period 5
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Station 1 – Rachel, Reese, Gavin,
Sophia
Station 2 – Ryan, James, Erin, Emma M
Station 3 – Josh, Ben, Casey, Emily
Station 4 – Miller, Christian, Emma T,
Ally
Station 5 – Tasha, Brendan, Justin,
Schuyler, Jack