1. Simple Machines

2. What are the 6 types of simple machines?
Inclined Plane
Flat, slanted surface

3. What are the 6 types of simple machines?
Wedge
Thick at one end, tapered to a sharp edge on the other

4. What are the 6 types of simple machines?
Screw
Inclined plane wrapped around a cylinder

5. What are the 6 types of simple machines?
Lever
Rigid bar that is free to rotate at a fulcrum
(comes in different CLASSES depending upon where the fulcrum is located)

6. What are the 6 types of simple machines?
Wheel and Axle
Two circular objects fastened together that rotate on an axis

7. What are the 6 types of simple machines?
Pulley
Grooved wheel and axel with a rope/chain around it
Can be fixed or moveable

8. What is a compound (or complex) machine?
A machine made up of two or more simple machines.

9. Define / Describe WORK
Work is done when a force causes an object to move in the direction that the force is applied.
If there is no movement, there is no work
The formula for work is: W = F x D
The unit for work is Joules (J)

10. Work (practice)
To help rearrange the furniture in your classroom you exert a force of 20N to push a desk 10m. How much work do you do?
A hydraulic lift exerts a 12,000N force to lift a car 2m. How much work does the lift do?

11. What is purpose of a machine?
To make work easier.
You put a force in (input force)
The machine puts a force out (output force)

12. How do machines make work easier?
1. They can change the amount of force (like a bat, which is a lever)
2. They can change the distance (ramp)
3. They can also change the direction to make lifting load easier (fixed pulley is example)

13. Mechanical Advantage
The number of times a force you exert is multiplied by the machine.
MA = Output Force ÷ Input Force

14. Mechanical Advantage
If you exert a force of 20N on a can opener and the opener exerts a force of 60N on the can, then what is the MA?
If you exert an input force of 20N and the machine produces an output force of 10N, then what is the MA?

15. Efficiency of Machines
A comparison of the output work to input work in percent
And ideal machine would have 100% efficiency, but some work is lost to friction, so actual efficiency is always less
Efficiency = output work ÷ input work × 100

16. Efficiency Practice
You cut the lawn with a hand lawn mower. You do 250,000J of work to move the mower. If the work done by the mower in cutting the lawn is 200,000J. What is the efficiency of the lawn mower?

17. Power HOW FAST work is being done
The same amount of work done faster will produce more power
Power = work ÷ time

18. Power Practice!
A motor performs 300,000 Joules of work in 5s. What is the power produced by the motor?