Simple and Compound Simple and Compound MachinesMachines

Identifying Simple MachinesIdentifying Simple Machines

What is the difference between a What is the difference between a simple and compound machine?simple and compound machine?

A simple machine is a machine with A simple machine is a machine with few or no moving parts. Simple few or no moving parts. Simple machines make work easier.machines make work easier.

A compound machine is a machine A compound machine is a machine with two or more simple machines with two or more simple machines working together to make work working together to make work easier.easier.

What is work?What is work?

You are doing work when you use a You are doing work when you use a forceforce to cause a to cause a motion.motion.

MotionMotion is the changing of position of is the changing of position of an object in reference to a starting an object in reference to a starting point.point.

Work is the transfer of Work is the transfer of energy energy through through motionmotion..

In order for work to take place, a In order for work to take place, a force force must be exerted through a must be exerted through a distancedistance..

How much work?How much work?

The amount of work depends on two The amount of work depends on two things:things:

The amount of The amount of Force (F) Force (F) exerted.exerted. The The Distance (d) Distance (d) over which the over which the

ForceForce is applied. is applied. The Equation for Work:The Equation for Work:

RememberRemember

There are two factors to keep in mind There are two factors to keep in mind when deciding whether work is being when deciding whether work is being done:done:

Something has to move.Something has to move. The The motion motion must be in the direction must be in the direction

of the applied of the applied ForceForce..

How does a simple machine make How does a simple machine make work easier?work easier?

Transferring the Transferring the ForceForce from one from one place to anotherplace to another

Changing the direction of a Changing the direction of a ForceForce Increasing the magnitude of a Increasing the magnitude of a ForceForce Increasing the distance or speed of a Increasing the distance or speed of a

ForceForce

Types of Simple MachinesTypes of Simple Machines

LeverLever

A straight rod or board that pivots on A straight rod or board that pivots on a point known as a fulcrum. The a point known as a fulcrum. The fulcrum can be moved depending on fulcrum can be moved depending on the weight of the object to be lifted the weight of the object to be lifted or the force you wish to exert. or the force you wish to exert. Pushing down on one end of a lever Pushing down on one end of a lever results in the upward motion of the results in the upward motion of the opposite end of the fulcrum.opposite end of the fulcrum.

ExamplesExamples

GearGear

Two toothed wheels fit together Two toothed wheels fit together either directly or through a chain or either directly or through a chain or belt so one wheel will turn the other. belt so one wheel will turn the other. Some gears may have a screw or a Some gears may have a screw or a toothed shaft in place of one of the toothed shaft in place of one of the wheels. A gear may also be a wheels. A gear may also be a combination of toothed wheels that combination of toothed wheels that produces a certain speed.produces a certain speed.

ExamplesExamples

Inclined PlaneInclined Plane

A sloping surface, such as a ramp. A sloping surface, such as a ramp. An inclined plane can be used to An inclined plane can be used to alter the effort and distance involved alter the effort and distance involved in doing work, such as lifting loads.in doing work, such as lifting loads.

ExamplesExamples

ScrewScrew

An inclined plane wrapped around a An inclined plane wrapped around a shaft or cylinder. This inclined plane shaft or cylinder. This inclined plane allows the screw to move itself or to allows the screw to move itself or to move an object or material move an object or material surrounding it when rotated.surrounding it when rotated.

ExamplesExamples

WedgeWedge

Two inclined planes joined back to Two inclined planes joined back to back. Wedges are used to split back. Wedges are used to split things.things.

ExamplesExamples

Wheel and AxleWheel and Axle

A wheel and axle has a larger wheel (or A wheel and axle has a larger wheel (or wheels) connected by a smaller cylinder wheels) connected by a smaller cylinder (axle) and is fastened to the wheel so that (axle) and is fastened to the wheel so that they turn together. When the axle is they turn together. When the axle is turned, the wheel moves a greater turned, the wheel moves a greater distance than the axle, but less force is distance than the axle, but less force is needed to move it. The axle moves a needed to move it. The axle moves a shorter distance, but it takes greater force shorter distance, but it takes greater force to move it.to move it.

ExamplesExamples

PulleyPulley

A wheel that usually has a groove A wheel that usually has a groove around the outside edge. This around the outside edge. This groove is for a rope or belt to move groove is for a rope or belt to move around the pulley. Pulling down on around the pulley. Pulling down on the rope can lift an object attached the rope can lift an object attached to the rope. Work is made easier to the rope. Work is made easier because pulling down on the rope is because pulling down on the rope is made easier due to gravity.made easier due to gravity.

ExamplesExamples