1. Work, Power, and Machines
Ch # 9 Notes
Work, Power, and Machines

2. 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)

3. 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

4. Mechanical advantage- (MA) a quantity that measures how much a machine multiplies force or distance
Mech Ad = Output force / Input force
Input distance / output distance

5. Chapter 9.2 notes
Simple machines- 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. 6 simple machines
Wheel and Axle

7. Compound machine- is a machine made of more than one simple machines.
A bike and a car are examples of compound machines.

8. Chapter 9.3 Notes
Potential energy- 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

9. Kinetic energy- 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

10. Mechanical energy- is the sum of the kinetic and potential energy of a large scale system

11. 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

12. Work Cited
“Six Simple Machines”. April 14,
“Wheel and Axle”. April 16,
“Roller Coaster”. April 17,