Simple Machines A Simple Machine Simple machines help

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Simple Machines

Simple Machines

A Simple Machine? Simple machines help us do work. Ø Machines make work easy.

A Simple Machine? Simple machines help us do work. Ø Machines make work easy. Ø

So What? Ø Simple machines make work easier Ø Simple machines either change the

So What? Ø Simple machines make work easier Ø Simple machines either change the amount of force on an object or change the direction of the force Ø Machines DON’T diminish the amount of work we do—they just make it easier! Ø Two or more SIMPLE machines make a COMPLEX machine!

What is mechanical advantage? The number of times a machine multiplies the effort or

What is mechanical advantage? The number of times a machine multiplies the effort or input force.

Mechanical Advantage ® It is useful to think about a machine in terms of

Mechanical Advantage ® It is useful to think about a machine in terms of the input force (the force you apply) and the output force (force which is applied to the task). ® When a machine takes a small input force and increases the magnitude of the output force, a mechanical advantage has 5

What is a Simple Machine? Ø Simple machines have few or no moving parts.

What is a Simple Machine? Ø Simple machines have few or no moving parts. Ø There are 6 kinds of simple machines.

What are the 6 kinds of simple machines? 1. Inclined plane 4. Wheel and

What are the 6 kinds of simple machines? 1. Inclined plane 4. Wheel and axle 2. Wedge 5. Pulley 3. Screw 6. Lever

An Inclined Plane?

An Inclined Plane?

Actually, an Inclined Plane… Ø …inclined plane is like a flat board that is

Actually, an Inclined Plane… Ø …inclined plane is like a flat board that is higher on one end. Ø …inclined plane makes work easier.

Inclined Plane An inclined plane is a slanting surface. It is easier to push

Inclined Plane An inclined plane is a slanting surface. It is easier to push an object up an inclined plane than to lift the object the same height This is because your effort is spread out over a larger distance. Lifting an object to the same height requires A LOT MORE effort over a shorter distance

Inclined Plane Shorter distance MORE EFFORT Longer Distance LESS EFFORT

Inclined Plane Shorter distance MORE EFFORT Longer Distance LESS EFFORT

Can you think of some other inclined planes?

Can you think of some other inclined planes?

A Wedge?

A Wedge?

Actually, a wedge… … is two inclined planes pushed together like a V. Ø

Actually, a wedge… … is two inclined planes pushed together like a V. Ø …pushes things away from each other. Ø …split things. Ø

Wedge A wedge has one slanting slide that ends in a sharp edge which

Wedge A wedge has one slanting slide that ends in a sharp edge which can cut things apart. A wedge is an inclined plane that decreases the force needed to break apart something.

Can you think of some other wedges?

Can you think of some other wedges?

A Screw(ge)?

A Screw(ge)?

Actually, a screw… …is an inclined plane wrapped around a post or cylinder (the

Actually, a screw… …is an inclined plane wrapped around a post or cylinder (the inclined plane allows the screw to move itself when rotated). Ø …holds things together and can make them go up and down. Ø

To help you visualize this better… ®# of Threads is equal to Length of

To help you visualize this better… ®# of Threads is equal to Length of the inclined plane Picture from http: //www. nvsd 44. bc. ca/sites/Reports. View. One. Pop. M. asp? RID=3812

Can you think of some other screws?

Can you think of some other screws?

Wheels and axles?

Wheels and axles?

Actually, a wheel and axle… Ø …is a pole that goes through the wheel

Actually, a wheel and axle… Ø …is a pole that goes through the wheel which allows the wheel to turn

Can you think of some other wheels and axles?

Can you think of some other wheels and axles?

Pulleys?

Pulleys?

Pulleys A pulley uses wheels and rope to raise, lower or move a load.

Pulleys A pulley uses wheels and rope to raise, lower or move a load. Pulleys make lifting a load easier by changing the direction of your effort force A pulley is made up 3 parts: Pulley Load Effort (force)

Parts Of A Pulley Effort (force) Load

Parts Of A Pulley Effort (force) Load

Types of Pulleys There are different types of pulleys. Single Pulley Moveable Pulley One

Types of Pulleys There are different types of pulleys. Single Pulley Moveable Pulley One wheel involved Doesn’t increase the effort force; changes the direction Multiple wheels involved Multiplies the force based on number of strings.

Can you think of some other pulleys?

Can you think of some other pulleys?

Lever?

Lever?

Lever A lever is a bar that rests on a pivot. Levers make it

Lever A lever is a bar that rests on a pivot. Levers make it easy to lift things because they magnify our effort Levers are made up 4 parts: Lever Fulcrum Load Effort

Parts of Lever Bar of stiff material Load The mass to move Effort Fulcrum

Parts of Lever Bar of stiff material Load The mass to move Effort Fulcrum Force of the person The pivot

Class One Lever There are 3 major classes of levers Class ONE Fulcrum is

Class One Lever There are 3 major classes of levers Class ONE Fulcrum is in the middle between the load and the effort a seesaw

Class Two Lever There are 3 major classes of levers Class TWO The load

Class Two Lever There are 3 major classes of levers Class TWO The load is in the middle Fulcrum and effort at opposite ends a wheelbarrow

Class Three Lever There are 3 major classes of levers Class THREE Effort is

Class Three Lever There are 3 major classes of levers Class THREE Effort is in the middle between the load and the fulcrum tweezers, your arm

Can you think of some other levers?

Can you think of some other levers?

What is a Lever? a rigid bar that is free to turn about a

What is a Lever? a rigid bar that is free to turn about a fixed point called the fulcrum Every Lever has three (3) parts: Effort: Where force is placed. : e c n sta i s e R t is a h t ct e j b O ed v o m Fulcrum Pivoting Point

Efficiency is the ability of a machine to convert input work to output work.

Efficiency is the ability of a machine to convert input work to output work. Efficiency = output work ✕ 100% input work The efficiency of a real machine is always less than 100 percent because of friction

Calculating Efficiency Always express the number as a %

Calculating Efficiency Always express the number as a %

Efficiency Friction reduces efficiency by converting some work into heat Oil, or another lubricant,

Efficiency Friction reduces efficiency by converting some work into heat Oil, or another lubricant, can increase efficiency by reducing the number of contact points between surfaces.

Simple Machines Ø Simple machines can be put together in different ways to make

Simple Machines Ø Simple machines can be put together in different ways to make complex machinery

COMPOUND MACHINES ® Many familiar compound machines, such as a car, a washing machine,

COMPOUND MACHINES ® Many familiar compound machines, such as a car, a washing machine, or a clock, are combinations of hundreds or thousands of simple machines.

Compound Machine Corkscrew ® Inclined Plane ® Wedge ® Screw ® Lever ® Wheel

Compound Machine Corkscrew ® Inclined Plane ® Wedge ® Screw ® Lever ® Wheel and Axle

Compound Machine Jack ® Inclined ® Wedge ® Screw ® Lever Plane

Compound Machine Jack ® Inclined ® Wedge ® Screw ® Lever Plane

A Wedge in a Compound Machine: Stapler ® Staples are wedges: they cut through

A Wedge in a Compound Machine: Stapler ® Staples are wedges: they cut through paper because their ends are pointed in a wedge shape. ® Simple machines in a stapler: Wedge ® Lever ®

A Wedge in a Compound Machine: Scissors ® The cutting edge of scissors is

A Wedge in a Compound Machine: Scissors ® The cutting edge of scissors is a wedge. ® Simple machines in a pair of scissors: Wedge ® Lever ®

What type of machine? ® video

What type of machine? ® video

Vocabulary Simple machine mechanical advantage lever Fulcrum inclined plane pulley Screw wedge wheel &

Vocabulary Simple machine mechanical advantage lever Fulcrum inclined plane pulley Screw wedge wheel & axle Output force Input force compound machine