# Ch # 9 Notes - PowerPoint PPT Presentation

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Ch # 9 Notes . Work, Power, and Machines. Chapter 9.1 Notes. Work- quantity of energy transferred by a force when it is applied to a body and causes that body to move in the direction of the force. Has to move!!! Work = Force x Distance Work done is measured Joules (J).

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Ch # 9 Notes

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## Ch # 9 Notes

Work, Power, and Machines

### Chapter 9.1 Notes

• Work- quantity of energy transferred by a force when it is applied to a body and causes that body to move in the direction of the force. Has to move!!!

Work = Force x Distance

Work done is measured Joules (J)

• Power- a quantity that measures the rate at which work is done

Power = Work/time

Power is often measured in watts but horsepower is also a unit of power

• Mechanicaladvantage- (MA) a quantity that measures how much a machine multiplies force or distance

Mech Ad = Output force / Input force

Input distance / output distance

### Chapter 9.2 notes

• Simplemachines- one of the six basic types of machines of which all other machines are composed of.

The six simple machines

• Lever

• Pulley

• Wheel and axle

• Inclined plane

• Wedge

• Screw

### 6 simple machines

Wheel and Axle

• Compound machine- is a machine made of more than one simple machines.

• A bike and a car are examples of compound machines.

### Chapter 9.3 Notes

• Potentialenergy- the stored energy resulting from the relative position of objects in a system.

Gravitational potential energy equation

gPE = mass x free-fall acceleration x height

PE = mgh

So the higher up or the bigger the mass the more PE

• Kineticenergy- the energy of a moving object due to its motion

Kinetic energy equation

KE = ½ x mass x velocity squared

KE = ½ mv2

So the faster an object moves the greater the KE

• Mechanicalenergy- is the sum of the kinetic and potential energy of a large scale system

### Chapter 9.4 Notes

Top of hill has the greatest amount of PE

• The law of conservation of energy states that energy cannot be created or destroyed.

• Energy changes from potential energy to kinetic energy.

Bottom of hill has the greatest amount of KE

### Work Cited

• “Six Simple Machines”. April 14, 2008. http://www.coolschool.ca/lor/SC9/unit16/U16L04/SimpleMachinesImages.jpg

• “Wheel and Axle”. April 16, 2008. http://www.ed.uri.edu/SMART96/ELEMSC/SMARTmachines/images/logo.gif

• “Roller Coaster”. April 17, 2008. http://z.about.com/d/travelwithkids/1/0/w/C/coaster_330.JPG