Simple & Simple & Compound Compound Machines:Machines:

By:By:

Mr. ManningMr. Manning

What is a Machine What is a Machine again…?again…?

A machine is a device that helps make A machine is a device that helps make work easier.work easier.

A machine makes work easier by A machine makes work easier by changing the size or direction of a force.changing the size or direction of a force.

Types of Machines:Types of Machines:

All machines are made from the following All machines are made from the following six simple machines: six simple machines:

LeverLever Inclined planeInclined plane WedgeWedge ScrewScrew Wheel & AxleWheel & Axle PulleyPulley

Continued:Continued:

You’ve seen a couple of these machines You’ve seen a couple of these machines already- a screwdriver can be used as a already- a screwdriver can be used as a lever, and a ramp onto the highway as an lever, and a ramp onto the highway as an inclined plane.inclined plane.

The Human body uses simple machines.The Human body uses simple machines.

For example, muscles and bones form For example, muscles and bones form levers.levers.

Levers:Levers:

A lever is a simple machine consisting of A lever is a simple machine consisting of a bar that pivots at a fixed point, called a a bar that pivots at a fixed point, called a fulcrum.fulcrum.

Levers are used to apply a force to a Levers are used to apply a force to a load.load.

There are three classes of levers, based There are three classes of levers, based on the locations of the fulcrum, the load, on the locations of the fulcrum, the load, and the input force.and the input force.

A hammer being used to remove a nail A hammer being used to remove a nail from a piece of wood is a lever.from a piece of wood is a lever.

Lever: (1:14)Lever: (1:14)

Classes of Levers:Classes of Levers: An example of a An example of a first classfirst class lever can be the lever can be the

claw side of a hammer removing a nail, two claw side of a hammer removing a nail, two children on a see-saw, or a woman children on a see-saw, or a woman kayaking.kayaking.

An example of a An example of a second classsecond class lever is a lever is a farmer lifting and pushing a wheel barrow farmer lifting and pushing a wheel barrow full of soil.full of soil.

An example of a An example of a third classthird class lever can be a lever can be a girl curling a barbell at the gym, or a girl curling a barbell at the gym, or a carpenter hammering a nail into a table top.carpenter hammering a nail into a table top.

Classes of Levers: (2:21)Classes of Levers: (2:21)

Inclined Planes:Inclined Planes: An An inclined planeinclined plane is a simple machine that is a is a simple machine that is a

straight, slanted surface.straight, slanted surface. A ramp is an example of an inclined plane.A ramp is an example of an inclined plane. The Egyptians used inclined planes a lot to move The Egyptians used inclined planes a lot to move

the heavy materials needed to construct the Great the heavy materials needed to construct the Great Pyramids.Pyramids.

An inclined plane does not reduce the amount of An inclined plane does not reduce the amount of work because the object has to travel a greater work because the object has to travel a greater distance, but the work is easier. (example sliding, distance, but the work is easier. (example sliding, rather than lifting a piano into a truck)rather than lifting a piano into a truck)

Inclined Planes: (2:27)Inclined Planes: (2:27)

Wedges:Wedges: A A wedgewedge is a double inclined plane that is a double inclined plane that

moves.moves. A knife, for example, is an inclined that A knife, for example, is an inclined that

plane that makes task easier like cutting a plane that makes task easier like cutting a cold sweet watermelon on a hot day.cold sweet watermelon on a hot day.

Wedges allow you to exert force over an Wedges allow you to exert force over an increased distance.increased distance.

The greater the distance you move the The greater the distance you move the wedge, the greater the force it applies on wedge, the greater the force it applies on the object.the object.

Wedges: (2:02)Wedges: (2:02)

Screw:Screw:

A A screw screw is an inclined plane that is is an inclined plane that is wrapped in a spiral.wrapped in a spiral.

When a screw is rotated, a small force is When a screw is rotated, a small force is applied over the long distance along the applied over the long distance along the inclined plane of the screw.inclined plane of the screw.

In other words, you apply a small input In other words, you apply a small input force over a large distance, while the screw force over a large distance, while the screw exerts a large output force over a small exerts a large output force over a small distance.distance.

IS THAT A FACT!IS THAT A FACT!

Both a jar lid and the top of a jar are Both a jar lid and the top of a jar are

screws. The ridges on the jar and on the screws. The ridges on the jar and on the

lid act as screws, holding the jar and the lid act as screws, holding the jar and the

lid together.lid together.

Screw: (2:54)Screw: (2:54)

Wheel & Axle:Wheel & Axle:

Did you know that when you turn a Did you know that when you turn a doorknob you are using a machine?doorknob you are using a machine?

A doorknob is an example of a A doorknob is an example of a wheel and wheel and axle, axle, a simple machine consisting of two a simple machine consisting of two circular objects of different sizes.circular objects of different sizes.

Examples: fishing reel handle, door knob, Examples: fishing reel handle, door knob, wrench, ferris wheel, screwdriver, steering wrench, ferris wheel, screwdriver, steering wheel, etc.wheel, etc.

Continued:Continued:

When a small input force is applied to the When a small input force is applied to the wheel, it rotates through a circular distance.wheel, it rotates through a circular distance.

As the wheel turns, so does the axle. But As the wheel turns, so does the axle. But because the axle is smaller than the wheel, because the axle is smaller than the wheel, it rotates through a smaller distance, which it rotates through a smaller distance, which makes the output force larger than the input makes the output force larger than the input force.force.

Wheel & Axle: (1:35)Wheel & Axle: (1:35)

Pulley:Pulley:

A A pulleypulley is a simple machine consisting of a is a simple machine consisting of a grooved wheel that holds a rope or a cable. grooved wheel that holds a rope or a cable.

A load is attached to one end of a rope, and A load is attached to one end of a rope, and an input force is applied to the other end.an input force is applied to the other end.

There are two kinds of pulleys- fixed and There are two kinds of pulleys- fixed and movable, which can combine to form a movable, which can combine to form a block and tackle.block and tackle.

Pulley: (1:33)Pulley: (1:33)

Continued:Continued: A A fixed pulleyfixed pulley only changes the direction of a only changes the direction of a

force.force. Example: an ElevatorExample: an Elevator

A A movable pulleymovable pulley is attached to the object as it is is attached to the object as it is moved.moved.

A block and tackle uses a combination of pulleys, A block and tackle uses a combination of pulleys, like on a large crane used to lift extremely heavy like on a large crane used to lift extremely heavy objects.objects.

Movable & Fixed Pulley:Movable & Fixed Pulley:

Compound Machine:Compound Machine:

Did you know that you are surrounded by Did you know that you are surrounded by machines?machines?

Most of the machines in the world are compound Most of the machines in the world are compound machines, machines that are made of two or machines, machines that are made of two or more simple machines.more simple machines.

Example: A can opener is composed of a lever, Example: A can opener is composed of a lever, wedge, and wheel & axle.wedge, and wheel & axle.

Compound Machine: (2:51)Compound Machine: (2:51)