1. The Advantage of Machines

2. What is a Machine? Machine – any device that makes work easier
REMEMBER:
-- Work is the transfer of energy
-- Work can also be thought of as the amount of energy required to move an object a certain distance with a specific force
We often think of machines as a crazy device with all sorts of wires and buttons and gears, but in reality all of these machines are made up of the six simple machines

3. The Six Simple Machines
Simple Machine – any device that does work with only one movement
The six simple machines are:
-- Wheel and axle
-- Screw
-- Lever
-- Inclined Plane
-- Pulley
-- Wedge
We will look more as to how this simple machines make work easier later.

4. How Machines Make Work Easier
Machines make work easier in one of three ways:
1. Changing the amount of force you exert.
2. Changing the distance over which you exert the force.
3. Changing the direction in which you exert the force.
*** Of course, these all make sense, as work is the product of force x distance, but remember work still has to go in the direction of the force ***

5. The Ideal Machine
Because work is energy, and energy is always conserved, the work in to a machine should equal the work out of a machine.
-- only works in an “ideal” machine, because some energy is lost due to friction
In reality, work out will always be less than work in due to friction

6. Moto Perpetuo
In a perfect world, no energy would be lost at all and a machine, once started could run forever.
We call these theoretical devices “Perpetual Motion Machines”
While scientists can come close to machines with zero energy loss, they have not yet made a perfect, ideal machine.

7. Three Types of Machines
Wedge
Screw
Inclined Plane

8. Three More Types of Machines
Pulley
Wheel & Axle
Three More Types of Machines
Levers

9. Inclined Plane

10. What is an Inclined Plane
Inclined Plane – a flat surface that is higher on one end
-- used to move objects to a higher or lower place
-- make the work of moving things easier
Examples: ramps, slides, stairs

12. Screw Screw – an inclined plane wrapped around a cylindrical post
-- as the screw is turned, the inclined plane moves through the resistance
-- thus, the load actually moves “up” the inclined plane

14. Wedge Wedge – two inclined planes put together
-- instead of the load, the wedge moves
-- the resistance does not move up the inclined plane, but rather the inclined plane moves through the resistance

15. Pulleys

16. What Are Pulleys?
Pulley – a rope, chain, or belt wrapped around a grooved wheel
-- pulleys are one of the six types of simple machines
-- pulley are actually a type of lever
We will define these parts a little bit later.
Fulcrum
Effort
Load

17. Types of Pulleys
There are two types of pulleys, based on the method in which the load (resistance) is attached to the pulley:
Fixed Pulley – the load is attached to one end of the pulley rope, and the pulley itself is attached to something that does not move
Moveable Pulley – the load is attached to the pulley itself, and the ropes allow the entire pulley to move

18. ? Fixed Pulleys Fixed pulleys change the direction of a force Fulcrum
Effort
Load

19. ? Moveable Pulleys A moveable pulley is free-moving
Moveable pulleys always make it easier to lift things.
Effort
Fulcrum ?
Load

20. Wheel and Axle

21. What is a Wheel and Axle?
Wheel and Axle – a simple machine made up of two wheels of different sizes that rotate together
-- usually used to overcome friction
-- like a pulley, a wheel is also a modified lever
Effort
Fulcrum
Load

22. Levers

23. What Are Levers?
Lever – a rigid bar that is free to move about a fixed point
-- a lever is one of the six types of simple machines
Examples of Levers:
-- see-saw (teeter-totter)
-- hammer
-- spoon
-- hockey stick

24. Parts of a Lever A lever consists of three parts:
Fulcrum – the fixed point around which the lever pivots
Effort Arm – the part of the lever that the effort force is applied to
-- measured from the fulcrum to the point at which force is applied
Resistance Arm – the part of the lever that applies the resistance force
-- measured from the fulcrum to the center of the resistance force

25. Illustration of the Parts of a Lever

26. Illustration of the Parts of a Lever

27. Three Classes of Levers
There are three classes (or types) of levers, which are based on the location of the fulcrum relative to the resistance and effort arms.
These three classes of levers are:
-- First-class levers
-- Second-class levers
-- Third-class levers

28. First-Class Levers
First-Class Lever – the fulcrum is located between the resistance arm and the effort arm
Examples: see-saw, scissors

29. Second-Class Levers
Second-Class Levers – the resistance is located between the effort force and the fulcrum
Examples: wheelbarrow, bottle opener

30. Third-Class Levers
Third-Class Levers – the effort force is located between the fulcrum and the resistance
Examples: rakes, shovels, baseball bats

31. Compound Machines
Compound Machine – any device made up of two or more simple machines
-- most “machines” that we think of are compound machines
-- some compound machines use chains or gears to help the energy from one machine transfer to another machines
Examples of compound machines:
-- pencil sharpener, computer, bicycle

32. Rube-Goldberg Device
A Rube-Goldberg device is a compound machine that performs a very simple task in a very difficult way, through a series of energy conversions between simple machines.
-- The game Mousetrap is an example of a Rube-Goldberg device.