Simple Machines&

Their Mechanical Advantages

Wedge

• It is used to push an object(s) apart.

• It is made up of two inclined planes. These planes meet and form a sharp edge.

• The edge can split things apart.

Wedge

fork and knife

Hammer

Spatula

fork (garden tool)

AxesSaw

Inclined Plane

• It is a flat surface that is higher on one end.

• You can use this machine to move an object to a lower or higher place

• Makes the work of moving things easier. You would need less energy and force to move objects with it.

Inclined Plane

Ladder

ramp

roller coaster

traffic sign slope warning

dump truckbath tub

boat propeller

Lever• It is a board or bar that rests on a

turning point. This turning point is called the fulcrum.

• An object that a lever moves is called the load.

• The closer the object is to the fulcrum, the easier it is to move.

fulcrum

lever

load

Hammer

Teeter-totter

Lever

wheel barrel

can opener

Pulley• It is made up of a wheel

and a rope. The rope fits on the groove of the wheel. One part of the rope is attached to the load.

• When you pull on one side of the it, the wheel turns and the load will move.

• This device allows you to move loads up, down, or sideways.

grove

rope

load

wheel

Pulley

Sailboat

Movie screen

crane

mini blinds

mini blinds

Screw• It is made from another

simple machine. • It is actually an inclined

plane that winds around itself. It has ridges and is not smooth like a nail.

• Some of them are used to lower and raise things.

• They are also used to hold objects together.

ridges

inclined plane

Screw

mini blinds

screw lid jar

door lock

drill bits

swivel piano stool

Wheel and Axle• It has an axle which is a rod that

goes through the wheel. • The axle lets the wheel turn. • Together, these devices allow things

to be moved easily from place to place.

axlewheel

axle

wheel

Wheel and Axle

mini blindsclock

wagon

BicycleSkateboard

VHS tape

Kinds of Lever

(Fo)

(Fi)

screwdriver

(Fo)(Fi)

wheel barrel

(Fo)(Fi)

third-class lever

hockey stick

• There are three different kinds of levers.

• The location of the fulcrum, resistance arm, and effort arm is what makes them different

Kinds of Lever• All levers have two arms, called the effort

arm and the resistance arm.

fulcrum

Effort Arm Resistance Arm

E R

Kinds of Lever• The effort arm is the distance from the

fulcrum and the effort.

fulcrum

Effort Arm

E

Kinds of Lever• The resistance arm is the distance from the

fulcrum and the resistance.

fulcrum

Resistance Arm

R

A First-Class LeverThe fulcrum

is located between the force and resistance.

fulcrum

E Rload(Fi)

(Fo)FORCE

IN

FORCEOUT

Resistance Arm

A Second-Class LeverIs set-up so that the resistance is between

the force and fulcrum

fulcrum

Resistance Arm

load

(Fi)

FORCEIN

(Fo)

FORCEOUT

The force is between the resistance and the fulcrum.

fulcrum

Fish(Fi)

FORCEIN

(Fo)

FORCEOUT

HandResistanceEffort

A Third-Class Lever

Lever Equation

fulcrum

Resistance Arm

E R

Effort Arm

This equation can be used to find unknowns:

Effort Force X Effort Arm Length

=

Resistance Force X Resistance Arm Length

Finding Lever UnknownsHow much force is needed to move a rock

that weighs 100 pounds using a lever with an arm length of four feet and a resistance arm length of one foot?

EFFORTARM

(4 ft)rock100 lbs

RRESISTANCE

ARM(1 ft.)

(Fr)

RESISTANCEFORCE

(Fe)

EFFORTFORCE

Finding Lever UnknownsHow much force is needed to move a rock

that weighs 100 pounds using a lever with an arm length of four feet and a resistance arm length of one foot?

Effort Force X Effort Arm Length

=

Resistance Force X Resistance Arm Length

Finding Lever UnknownsHow much force is needed to move a rock

that weighs 100 pounds using a lever with an arm length of four feet and a resistance arm length of one foot?

Effort Force X 4 ft.

=

Resistance Force X Resistance Arm Length

Finding Lever UnknownsHow much force is needed to move a rock

that weighs 100 pounds using a lever with an arm length of four feet and a resistance arm length of one foot?

Effort Force X 4 ft.

=

100 lbs. X Resistance Arm Length

Finding Lever UnknownsHow much force is needed to move a rock

that weighs 100 pounds using a lever with an arm length of four feet and a resistance arm length of one foot?

Effort Force X 4 ft.

=

100 lbs. X 1 ft.

Finding Lever UnknownsHow much force is needed to move a rock

that weighs 100 pounds using a lever with an arm length of four feet and a resistance arm length of one foot?

Effort Force X 4 ft.

=

100 lbs. per ft.

Finding Lever UnknownsHow much force is needed to move a rock

that weighs 100 pounds using a lever with an arm length of four feet and a resistance arm length of one foot?

Effort Force

=

100 lbs. per ft. / 4 ft.

Finding Lever UnknownsHow much force is needed to move a rock

that weighs 100 pounds using a lever with an arm length of four feet and a resistance arm length of one foot?

Effort Force

=

25 lbs.

A Lever’s Mechanical Advantage

The mechanical advantage (M.A.) of a lever is determined by dividing the length of the effort arm by the length of the resistance arm.

M.A.

=

Effort Arm / Resistance Arm

A Lever’s Mechanical Advantage

What is the mechanical advantage for a lever with an effort arm of 6 meters and a resistance arm of 1.5 meters?

EFFORTARM(6 m)

R(1.5m)

RESISTANCEARM

A Lever’s Mechanical Advantage

What is the mechanical advantage for a lever with an effort arm of 6 meters and a resistance arm of 1.5 meters?

M.A.

=

Effort Arm / Resistance Arm

A Lever’s Mechanical Advantage

What is the mechanical advantage for a lever with an effort arm of 6 meters and a resistance arm of 1.5 meters?

M.A.

=

6 m / Resistance Arm

A Lever’s Mechanical Advantage

What is the mechanical advantage for a lever with an effort arm of 6 meters and a resistance arm of 1.5 meters?

M.A.

=

6 m / 1.5 m

A Lever’s Mechanical Advantage

What is the mechanical advantage for a lever with an effort arm of 6 meters and a resistance arm of 1.5 meters?

M.A. = 9

The mechanical advantage of this lever is 9. This means that the lever multiplied the

effort 9 times.

A Wheel and Axle’s Mechanical Advantage

The mechanical advantage (M.A.) for a wheel and axle is determined by dividing the diameter of the wheel

wheel

diameter

A Wheel and Axle’s Mechanical Advantage

The mechanical advantage (M.A.) for a wheel and axle is determined by dividing the diameter of the wheel by the diameter of the axle.

Axle

wheel

diameter

A Wheel and Axle’s Mechanical Advantage

What is the mechanical advantage of the wheel that has a diameter of 25 cm and an axle with a diameter of 2 cm?

Axle

wheel

diameter 25 cm

2 cm

A Wheel and Axle’s Mechanical Advantage

Axle

wheel

diameter 25 cm

2 cm

mechanical advantage (M.A.) =

diameter of the wheel / the diameter of the axle

A Wheel and Axle’s Mechanical Advantage

Axle

wheel

diameter 25 cm

2 cm

mechanical advantage (M.A.) =

25 cm / the diameter of the axle

A Wheel and Axle’s Mechanical Advantage

Axle

wheel

diameter 25 cm

2 cm

mechanical advantage (M.A.) =

25 cm / 2 cm

A Wheel and Axle’s Mechanical Advantage

Axle

wheel

diameter 25 cm

2 cm

mechanical advantage (M.A.) =

12.5

The mechanical advantage of this

wheel with this axle is 12.5.

Mechanical Advantage Of A Fixed Pulley

The mechanical advantage (M.A.) of a moveable pulley is determined by the number of supporting

ropes.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

The mechanical advantage (M.A.) of a fixed pulley with

one supporting strand is 1.

Mechanical Advantage Of A Fixed Pulley

The mechanical advantage (M.A.) of a moveable pulley is determined by the number of supporting

ropes.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

One supporting strand.

The effort needed to lift a 10 gram weight is 10 grams (10/1).

Mechanical Advantage Of A Moveable Pulley

The mechanical advantage (M.A.) of a moveable pulley is determined by the number of supporting

ropes.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

The mechanical advantage (M.A.) of a moveable pulley with two supporting

strand is 2.

Mechanical Advantage Of A Moveable Pulley

The mechanical advantage (M.A.) of a moveable pulley is determined by the number of supporting

ropes.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Two supporting strands

The effort need to lift a 10 gram weight is 5

grams (10/2).

Inclined Plane

FORCE

RESISTANCE

INCLINED PLANE

Mechanical Advantage of An Inclined Plane

The mechanical advantage (M.A.) of an inclined plane is the length of the incline divided by its

height.

Incline

Height

Mechanical Advantage of An Inclined Plane

A man is using an 8 foot board to slide things into the back of his

truck. The truck is 2.5 feet

from the ground. What

is the mechanical

advantage of this incline?

Length of incline(8 ft.)Height

of Plane

(2.5 ft.)

Mechanical Advantage of An Inclined Plane

mechanical advantage (M.A.) of an inclined plane =

the length of the incline / by its height

Length of incline(8 ft.)Height

of Plane

(2.5 ft.)

Mechanical Advantage of An Inclined Plane

mechanical advantage (M.A.) of an inclined plane =

8 ft. / by its height

Length of incline(8 ft.)Height

of Plane

(2.5 ft.)

Mechanical Advantage of An Inclined Plane

mechanical advantage (M.A.) of an inclined plane =

8 ft. / 2.5 ft.

Length of incline(8 ft.)Height

of Plane

(2.5 ft.)

Mechanical Advantage of An Inclined Plane

mechanical advantage (M.A.) of an inclined plane =

3.2

Length of incline(8 ft.)Height

of Plane

(2.5 ft.)

This means the effort is

multiplied by 3.2 when using this inclined plane.

Wedge

Screw

This simple demonstration shows how a screw is actually an inclined plane.

MaterialsPencilPaperColored felt tip markerScissors

ScrewProcedure1. Cut a right triangle from the paper. The

dimensions should be about 5 inches, by 9 inches, by 10.3 inches.

2. Use the felt tip marker to color the longest edge (10.3 inches) of the triangle.

3. Position the shortest side (5 inches) of the triangle along the side of the pencil and then evenly wrap the paper around the pencil by rolling the pencil.

Screw

Websites• http://www.cosi.org/files/Flash/simpMach/sm1.swf

• http://teacher.scholastic.com/dirtrep/simple/invest.htm

• Animation Pulley• http://library.thinkquest.org/J002079F/pulley2.htm

• Lever Classifications• http://library.thinkquest.org/J002079F/lever.htm• Simple Machine

• http://www.harcourtschool.com/activity/machines/simple_machines.htm