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