Simple Machines

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# Simple Machines - PowerPoint PPT Presentation

Simple Machines. Essential Questions. What is the purpose of the simple machines?. Simple Machine Types. There are 6 basic kinds of simple machines. These are: Inclined Plane Wedge Screw Levers Wheel and Axle Pulley. Inclined Plane. An inclined plane is a flat, slanted surface.

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### Simple Machines

Essential Questions
• What is the purpose of the simple machines?
Simple Machine Types
• There are 6 basic kinds of simple machines.
• These are:

Inclined Plane

Wedge

Screw

Levers

Wheel and Axle

Pulley

Inclined Plane
• An inclined plane is a flat, slanted surface.
• An example of an inclined plane is a ramp.
• The longer the inclined plane, the less input force you need to push or pull an object.
Friction
• Even though an inclined plane has no moving parts, work is lost due to friction.
• This is because friction comes from the bottom of the box rubbing against the ramp.
Wedge
• A wedge is a device that is thick at one end and tapers to a thin edge at the other end. A wedge is used to cut through an object.
• You can think of a wedge as an inclined plane that moves.
Wedge
• The longer and thinner the wedge is, the less input force is required.
• An example of a wedge is: an axe, a knife, a screwdriver, boat.
Screw
• A screw can be thought of as an inclined plane wrapped around a cylinder.
• An example of a screw is a jar lid, a bolt, and a faucet.
Levers
• A lever is a rigid bar that is free to pivot or rotate around a fixed point.
• The fixed point that a lever pivots around is called the fulcrum.
• There are 3 classes of levers.
First-Class Levers
• First class levers have the fulcrum located between the input force and output force.
• For example, scissors, seesaw, and pliers are first-class levers.
Second-Class Levers
• Second-class levers have the fulcrum located closer to the output force.
• Examples of second-class levers are nutcrackers, doors, bottle openers, and wheelbarrows.
Third-class Levers
• Third-class levers have the fulcrum located closer to the input force.
• Examples of third-class levers are fishing poles, shovels, and baseball bats.
• BrainPop Video
Wheel and Axle
• A wheel and axle is a simple machine made of 2 circular or cylindrical objects (wheels)that are fastened together and rotate around a common object (axle).
Wheel and Axle
• The larger object is called the wheel and the smaller object is called the axle.
• An example of a wheel and axle is a screwdriver, door knob, or steering wheel.
• BrainPOP video
Pulley
• A pulley is a grooved wheel with a rope wrapped around it.
• You use a pulley by pulling on the rope.
• A pulley that you attach to a structure is called a fixed pulley.
Pulley
• If you attach a pulley to the object you wish to move, then you are using a movable pulley.
• If you combine fixed and movable pulleys, you can make a pulley system.
Compound Machine
• A machine that utilizes two or more simple machines is called compound machine.
• Examples are: bicycle, pencil sharpener, bulldozer.
Compound Machine
• Gears form a compound machine with one wheel and axle linked to another wheel and axle.
• What machine works with gears? Bicycle
Mega Point Review
• How does a doorknob work?

The knob is a wheel and the axle pulls in the closer so the door will open.

• What on a lever does not move?

Fulcrum

Mega Point Review
• How are wedges and screws related?

Both have inclined planes.

• What are three ways in which a machine can make work easier?

By changing the force, distance, or direction

Mega Point Review
• How can you determine if work is done on an object?

Work is done when an object moves.