# Simple Machines - PowerPoint PPT Presentation

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Simple Machines. Guided Reading and Study. Inclined Plane. 2. Flat, sloped surface 3. IMA : length / height 4. The following are true: a) Input force less than output force b) A ramp is an example d ) Allows you to exert a force over a longer distance

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Simple Machines

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## Simple Machines

### Inclined Plane

• 2. Flat, sloped surface

• 3. IMA: length / height

• 4. The following are true:

• a) Input force less than output force

• b) A ramp is an example

• d) Allows you to exert a force over a longer distance

• 5. The larger (longer) the incline (less steep) the less input forceis needed to move an object

### Wedge

• 6. Thick at one end and tapers to a thin edge at the other end

• Changes direction of the force

• Examples: axe, zipper, knife, teeth…

• 7. True – A wedge is an inclined plane (or 2 back to back) that can move

• 8. True – longer, thinner wedges have a higher MA

### Screw

• 9. An inclined plane wrapped around a cylinder (Examples: screw, bottle cap (lid), curving parking ramp)

• Multiples force (you input less force over a larger distance), can also change the direction of force

• 10. The spiral inclined plane forms the threadsof a screw

• 11. The input force is applied to the top of the screw. As the screw turns the threads exert on output force on the wood.

### Lever

• 12. A rigid bar that pivots or rotates around a fixed point.

• 13. The fixed point that a lever pivots around is called the fulcrum

### Lever

14. The following are true

• a) A lever increases the effect of your input force

• b) There are 3 different types of levers

• c) A lever changes the direction of your input force

• 15.

• Fulcrum

• 16.

2nd Class

1st Class

3rd Class

### Lever

• How levers make work easier depends on which class lever is being used.

• 1st class: changes direction, can multiply force or distance

• 2nd class: multiplies force

• 3rd class: multiplies distance

Input force

Output force

Fulcrum

Input force

Output force

Fulcrum

Output force

Input force

Fulcrum

### Lever

• 17.

• IMA: distance from effort (IF) to fulcrum

distance from load (OF) to fulcrum

### Wheel and Axle

• 18. 2 circular objects fastened together that rotate around a common axis. The circle with the larger radius is the wheel

• If input is turning the wheel: multiplies force

• If input is turning the axle: multiplies distance

• Examples: Steering wheel, screw driver, door knob

### Wheel and Axle

• 19. IMA = radius of wheel

### Pulley

• 20. Made of a grooved wheel with a rope or cable wrapped around it.

• IMA: number of segments of rope that support the load

• Examples are found on: flag poles, sail boats, construction cranes

• 21. Type that changes the direction of input force = fixed pulley

• 22. IMA of 2: moveable pulley

• There are also block and tackle pulleys

### Simple Machines in the Body

• 23. Most of the levers in the body consist of bones and muscles

• 24. Your muscles are attached to your bones by tough connective tissue called tendons

• 25. In a living lever in your body the joint near where the tendon is attached to the boneacts as the lever’s fulcrum

3rd Class Lever!

• 26.

Output Force

Input Force

Fulcrum

### Simple Machines in the Body

• 27. Incisors are wedges

• 28. When you bite down on something, the wedge shape of your teeth produces enough force to break what you’re biting in half, just as an ax is used to split a log.

### Compound Machines

• 29. A machine that is made up of two or more simple machines.

• 30. You must know the mechanical advantage of each simple machine utilized in the compound machine. The IMA of a compound machine is the product of the IMAs of the simple machines making up the compound machine.