1. Work, Power, and Machines
Carrie

2. Key Information You have to have movement for work to be done!
VOCAB WORDS:
Work: the product of distance and the force in the direction an object moves #1
Joule: the SI unit of work. #2
Jordan

3. Is work being done ? Mowing the lawn? YES! Weight-lifting? YES!
Moving furniture up a flight of stairs ? YES!
Pushing against a locked door ? NO
Swinging a golf club ? YES!
Zach

4. Key Information VOCAB WORDS: Power: The Rate of Doing Work. #3
Watt: The SI unit of Power. #4
The faster you do work, the more power you do!
The slower you do work, the less power you do!
Carrie

5. Key Information
One horsepower is equivalent to approximately 750 Watts. c
VOCAB WORDS:
Horsepower: A common unit of Power. #5
Jordan

6. Key Information
Important Equations and Words:
W F D
P W T
Zach

7. Force: A push or a pull that acts on an object. #6
Key Information
Any part of a force that does not act in the direction of motion does no work on an object.
VOCAB WORD:
Force: A push or a pull that acts on an object. #6
Carrie

8. Key Information
Machines change the size of a force needed, the direction of a force, or the distance over which a force acts.
VOCAB WORDS:
Machine: A device that changes force. #7
Jordan

9. Key Information SIMPLE MACHINES: The Lever Wheel and Axle
A bar that is free to pivot #8
Fulcrum: the pivot point of a lever #9
Wheel and Axle
A lever that rotates in a circle #10
Inclined Plane
A slanted surface used to raise an object #11
The Wedge
An inclined plane that moves #12
The Screw
An inclined plane wrapped around a cylinder #13
The Pulley
A chain, belt, or rope wrapped around a wheel #14
Zach

10. First-Class Lever
The Fulcrum of a First-Class lever is always located between the input force and the output force.
Depending on the location of the Fulcrum, the mechanical advantage can be greater than 1, equal to 1, or less than 1.
Examples:
Seesaw, scissors, and tongs.
Carrie

11. Second-Class Lever
In a second-class lever, the output force is located between the input force and the Fulcrum.
The mechanical advantage is always greater than 1.
Example:
Wheelbarrow
Jordan

12. Third-Class Lever
The input force of a third-class lever is located between the Fulcrum and the output force
The mechanical advantage is always less than 1.
Examples:
Baseball bats, hockey sticks, and golf clubs.
Zach

13. Key Information
Because of friction, the work done by a machine is always less than the work done on a machine
VOCAB WORDS:
Friction: A force that opposes the motion of objects that touch as they move past each other. #15 C

14. Key Information
Because there is always some friction the efficiency of any machine is always less than 100%
Jordan

15. Key Information
Because friction is always present, the actual mechanical advantage of a machine is always less than the ideal mechanical advantages.
Carrie

16. Vocabulary words VOCAB WORDS:
Input Force: The force you exert on a machine. #16
Input Distance: The distance the Input Force acts through. #17
Work Distance: The work done by the Input Force acting through the Input Distance. #18
Output Force: The Force that is exerted by a machine. #19
Output Distance: The distance the Output Force is exerted through. #20
Work Output: the Output Force multiplied by the Output Distance. #21
Compound Machine: A combination of two or more machines that operate together. #22
Zach

17. Key Information Important Equations and Vocab Words:
Actual Mechanical Advantage: Equals the ratio of the Output to Input Force. #23
Ideal Mechanical Advantage: the mechanical advantage in the absence of friction. #24
Actual
Mechanical Output Force Input Force
Advantage
Ideal
Mechanical Input Output
Advantage Distance Distance
Jordan

18. Key Information Efficiency Work Work 100% Output Input
Efficiency: The percentage of the work input that becomes work output of a machine. #25
Carrie

19. Work, Power, and Machines