1. Simple Machines
Chapter 5
There are six types of machines that scientists call 'simple machines.'
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Edwin P. Davis, M.Ed.

2. Levers
Levers are one of the basic tools that were probably used in prehistoric times. Levers were first described about 260 BC by the ancient Greek mathematician Archimedes ( BC).
A lever is a simple machine that makes work easier for use; it involves moving a load around a pivot using a force.
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3. Lever
The Lever: The lever is simply a bar supported at a single point called the fulcrum. The positioning of the fulcrum changes the mechanical advantage of the lever.
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4. Type 1 Lever the pivot (fulcrum) is between the effort and the load.
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5. 1st Class Lever
A first-class lever is a lever in which the fulcrum is located between the input effort and the output load.
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6. 1st Class Levers Examples: Seesaw Trebuchet Crowbar Hammer Claw
Hand trucks
Pliers
Scissors
Shoehorn
Spud bar
Beam engine Wheel and axle.
Chopsticks with hand
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7. Type 2 Lever the load is between the pivot (fulcrum) and the effort.
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8. 2nd Class Lever
In a second class lever the input effort is located at the end of the bar and the fulcrum is located at the other end of the bar, opposite to the input, with the output load at a point between these two forces.
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9. 2nd Class Levers Dental elevator Nutcracker Paddle Curb bit
Examples
Dental elevator
Nutcracker
Paddle
Curb bit
Wheelbarrow
Wrench
Bottle opener
Diving Board
Crowbar
Push-up
Doorknob
Nail clippers
torsion spring
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10. Type 3 Lever the effort is between the pivot (fulcrum) and the load.:
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11. 3rd Class Lever the input effort is higher than the output load,
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12. 3rd Class Levers Examples Baseball bat Boat paddle Broom
Electric Gates
Fishing rod
Hockey stick
Mousetrap
Shovel
Stapler
Tweezers
Hammer
Tennis racket
The Human Arm
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13. Mechanical Advantage
The ratio of the output force to the input force is the mechanical advantage of a machine. The mechanical advantage of a machine can be calculated from the following equation.
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14. Mechanical Advantage (MA)
the factor by which a mechanism multiplies the force or torque put into it. :
                         
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15. Mechanical Advantage of the Levers
To find the MA of a lever, divide the effort arm length by the resistance arm length.
MA = effort arm length / resistance arm length
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16. Pulley
A pulley consists of a grooved wheel that turns freely in a frame called a block.
A pulley can be used to simply change the direction of a force or to gain a mechanical advantage, depending on how the pulley is arranged.
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17. Examples of Pulleys
                                    
                         
                                      
                                         
                                   
                                                          
                                                            
                                            
                                                                          
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18. Can you name all the pulleys?
block and tackle
rock climber pulleys
winch
oil derrick
clothesline pulley
marine pulley
steam shovel
flagpole pulley
window blinds
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19. Fixed Pulley
A fixed or class 1 pulley has a fixed axle. That is, the axle is "fixed" or anchored in place. A fixed pulley is used to change the direction of the force on a rope (called a belt). A fixed pulley has a mechanical advantage of 1.
A pulley is said to be a fixed pulley if it does not rise or fall with the load being moved. A fixed pulley changes the direction of a force; however, it does not create a mechanical advantage
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20. Fixed Pulley
"fixed" or anchored in place.
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21. Movable Pulley
A movable or class 2 pulley has a free axle. That is, the axle is "free" to move in space. A movable pulley is used to multiply forces. A movable pulley has a mechanical advantage of 2.
The mechanical advantage of a moveable pulley is equal to the number of ropes that support the moveable pulley. (When calculating the mechanical advantage of a moveable pulley, count each end of the rope as a separate rope).
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22. Movable Pulley
the axle is "free" to move in space.
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23. Diagrams of Pulleys Fixed pulley: Movable Pulley:
A fixed pulley changes the direction of a force; however, it does not create a mechanical advantage.
Fixed pulley:
The mechanical advantage of a moveable pulley is equal to the number of ropes that support the moveable pulley.
Movable Pulley:
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24. Block and Tackle
Compound A compound pulley is a combination of a fixed and a movable pulley system.
- A block and tackle is a compound pulley where several pulleys are mounted on each axle,
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25. Block & Tackle
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26. COMBINED PULLEY
The effort needed to lift the load is less than half the weight of the load.
The main disadvantage is it travels a very long distance. 
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27. Mechanical Advantage of Pulleys
An example of a rope and pulley system illustrating mechanical advantage .
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28. Inclined Plane
The Inclined Plane: Often referred to as a 'ramp' the inclined plane allows you to multiply your force over a longer distance.
In other words, you exert less force but for a longer distance. You do the same amount of work, it just seems easier because you spread it over time.
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29. Examples of Inclined Plane
An inclined plane lifts the front of this car.
                             An inclined plane is used to lift this heavy wheelbarrow into this trailer.
A short ramp is needed to equal these two steps.
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30. Mechanical Advantage - Inclined Plane
The mechanical advantage of an inclined plane is equal to the length of the slope divided by the height of the inclined plane.
While the inclined plane produces a mechanical advantage, it does so by increasing the distance through which the force must move.
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31. Wedge
The Wedge: A wedge works in a similar way to the inclined plane, only it is forced into an object to prevent it from moving or to split it into pieces. A knife is a common use of the wedge.
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32. Examples of Wedges
A door stop is a wedge that stops the door from moving.
                        The sharp edge of an ax is a wedge.
The sharp edge of the shovel is a wedge.
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33. Wedge – Mechanical Advantage
The mechanical advantage of a wedge can be found by dividing the length of either slope (S) by the thickness (T) of the big end. S
As an example, assume that the length of the slope is 10 inches and the thickness is 4 inches. The mechanical advantage is equal to 10/4 or 2 1/2. As with the inclined plane, the mechanical advantage gained by using a wedge requires a corresponding increase in distance. T
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34. Screw
The Screw: The screw is really just an inclined plane wrapped around a rod. It too can be used to move a load (like a corkscrew) or to 'split' and object (like a carpenter's screw).
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35. Examples of Screws
                    Some screws have a sharp point and are mostly used on wood.
                 Light bulbs have threads to screw them into sockets
                 The faucet has threads to screw the hose on.
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36. Efficiency
Efficiency is a measure of how much of the work put into a machine is changed into useful output work by the machine.
A machine with high efficiency produces less heat from friction so more of the input work is changed to useful output work.
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37. Calculating Efficiency
To calculate the efficiency of a machine, the output work is divided by the input work.
Efficiency is usually expressed as a percentage by this equation:
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38. Wheel & Axles
The wheel and axle is a simple machine. A wheel and axle is a lever that rotates in a circle around a center point or fulcrum. The larger wheel (or outside) rotates around the smaller wheel (axle).
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39. Wheel & Axles
A wheel is a lever that can turn 360 degrees and can have an effort or resistance applied anywhere on that surface. The effort or resistance force can be applied either to the outer wheel or the inner wheel (axle).
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40. Examples of Wheel & Axle
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41. Wheel and Axles pencil sharpener casters door knobs rolling pin
rotary dial telephone 
egg beater
bicycle
fan
windmill
roller skates
record player
wagon
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42. Mechanical Advantage
The mechanical advantage of a wheel and axle machine can be found by dividing the radius of the wheel by the radius of the axle.
Mechanical Advantage (M.A) = radius of the wheel / radius of the axle
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