Work
 Work is done on an object when energy is transferred to that object
 W = Force x distance
Stacking Hay

 The capacity to make something happen is
Energy
 The process of making something happen is
Work
 Energy and Work have the same units
KWH, Joules, Ft-Lbs., BTUs, Calorie, K-Calories

 Energy is not destroyed.
 Energy is transferred between objects.
(Energy in my body is used to slide a box across the table.)
 Energy is converted from one form to another.
(Energy in the box is converted to heat as the table heats up from the sliding box.)

A sliding box is moving, therefore we say it has motion energy or Kinetic
Energy.
Other examples of Kinetic Energy:
Moving car
Moving water
Moving wheel

 Batteries
 Gasoline
 Natural Gas
 Food IowaWaterQuality.org
 Water Towers
 A wound up alarm clock
 Toyota Prius battery http://www.uc.edu
http://electronics.howstuffworks.com

The Energy that is stored in an object
Examples:
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A stretched rubber band
A compressed spring
Lego
A boulder sitting at the top of a cliff
A Roller Coaster ready at the top of the track.
A charged battery
A voltage source
The Human body after eating.
Gasoline
The Sun www.travelblog.org
Steel Dragon 2000 roller coaster in Nagashima, Japan

Gravitational Potential Energy is the energy an object has because of its position relative to the earth.
grav. PE = weight x (height above ground)
Glen Canyon Dam in Utah uses the potential energy of the Colorado River water to produce more than a 1200 MegaWatts or power.
http://pinker.wjh.harvard.edu/

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A stretched rubber band ( elastic potential energy )
A compressed spring ( elastic potential energy )
A boulder sitting at the top of a cliff ( gravitatoinal potential energy )
A Roller Coaster ready at the top of the track. ( gravitational potential energy )
A charged battery ( chemical potential energy )
A voltage source ( electric potential energy per unit of charge )
The Human body after eating. ( chemical potential energy )
Gasoline ( chemical potential energy )
The future light and heat from the Sun ( nuclear potential energy )
A Dam ( gravitational potential energy )

 Toy car Flywheels
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A moving car
Flying Airplane
Earth, planets, the sun, the galaxies
Potters Wheels
Bicycle Wheels
Flywheel Energy Storage (FES)
 Fast Moving Roller Coasters at the bottom of the track

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Grav. PE  Kinetic Energy
Weight x h  ½ mv 2
Animation of Energy Transfer on a Roller Coaster: http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/energy/ce.html
A good explanation on Roller Coasters: http://howthingswork.virginia.edu/page1.php?QNum=1319

Engine Flywheels help smooth out the rotation of the shaft when a fluctuating torque is exerted on it by its pistons and cylinders.
http://www.craftsmanshipmuseum.com

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½ m v 2 (translational or linear KE) m is mass, and v is velocity/speed mass is how much matter is in the object weight = mass x gravity
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½ I w
2 (rotational KE)
I is the moment of inertia, or resistance to rotation , and w is rotational speed
Inertia is the resistance to a change in motion.
More massive objects have greater inertia.
I is the rotational equivalent of mass w is the angular speed expressed as revolutions per minute

The moment of inertia of an object describes how difficult it is to change its angular motion about its axis.
For example, consider two discs (A and
B) of the same mass but Disc A has a larger radius than disc B.
Assuming that there is uniform thickness and mass distribution, it requires more effort to rotate disc A
(change its angular velocity) because its mass is distributed farther from its axis of rotation: mass that is farther out from the axis must move more quickly than mass closer in.
In this case, disc A has a larger moment of inertia than disc B. http://en.wikipedia.org/wiki/Moment_of_inertia http://www.bsharp.org/physics/stuff/skater.html
 good video clips of skaters

Get something massive and accelerate it so that it is moving fast. Due to its mass it will resist slowing down. Massive objects in motion store a lot of
Kinetic Energy.
This is why high speed car crashes without restraint devices are often fatal. The energy has to go somewhere and if that energy is not transferred to the seatbelt then the energy will be transferred to other things, like the windshield, the pavement etc.

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Take the car apart.
Sketch its gear box
Determine the torque reduction from the wheels to the flywheel
From the flywheel to the wheels, is this speed reduction or torque reduction?
Do the wheels have more torque than the flywheel?
How much more?
How would you redesign the car to climb steep ramps?
What might be some limitations to your redesign?

 Power = Work/time
 Units for Power are:
Watts, Horsepower, foot-lbs/minute, BTU/hour