2. 22
Simple MachinesSimple Machines
A machine is a device that helps makeA machine is a device that helps make
work easier to perform by accomplishingwork easier to perform by accomplishing
one or more of the following functions:one or more of the following functions:
transferring a force from one place to another,transferring a force from one place to another,
changing the direction of a force,changing the direction of a force,
increasing the magnitude of a force, orincreasing the magnitude of a force, or
increasing the distance or speed of a force.increasing the distance or speed of a force.
3. 33
First Class LeverFirst Class Lever
In a first-class lever the fulcrum is locatedIn a first-class lever the fulcrum is located
at some point between the effort andat some point between the effort and
resistance forces.resistance forces.
Common examples of first-class leversCommon examples of first-class levers
include crowbars, scissors, pliers, tin snipsinclude crowbars, scissors, pliers, tin snips
and seesaws.and seesaws.
A first-class lever always changes theA first-class lever always changes the
direction of force (I.e. a downward effort forcedirection of force (I.e. a downward effort force
on the lever results in an upward movementon the lever results in an upward movement
of the resistance force).of the resistance force).
4. 44
Fulcrum is between EF (effort) and RF (load)Fulcrum is between EF (effort) and RF (load)
Effort moves farther than Resistance.Effort moves farther than Resistance.
Multiplies EF and changes its directionMultiplies EF and changes its direction
5. 55
Second Class LeverSecond Class Lever
With a second-class lever, the load is locatedWith a second-class lever, the load is located
between the fulcrum and the effort force.between the fulcrum and the effort force.
Common examples of second-class leversCommon examples of second-class levers
include nut crackers, wheel barrows, doors, andinclude nut crackers, wheel barrows, doors, and
bottle openers.bottle openers.
A second-class lever does not change theA second-class lever does not change the
direction of force. When the fulcrum is locateddirection of force. When the fulcrum is located
closer to the load than to the effort force, ancloser to the load than to the effort force, an
increase in force (mechanical advantage)increase in force (mechanical advantage)
results.results.
6. 66
RF (load) is between fulcrum and EFRF (load) is between fulcrum and EF
Effort moves farther than Resistance.Effort moves farther than Resistance.
Multiplies EF, but does not change its directionMultiplies EF, but does not change its direction
7. 77
Third Class LeverThird Class Lever
With a third-class lever, the effort force isWith a third-class lever, the effort force is
applied between the fulcrum and theapplied between the fulcrum and the
resistance force.resistance force.
Examples of third-class levers includeExamples of third-class levers include
tweezers, hammers, and shovels.tweezers, hammers, and shovels.
A third-class lever does not change theA third-class lever does not change the
direction of force; third-class levers alwaysdirection of force; third-class levers always
produce a gain in speed and distance and aproduce a gain in speed and distance and a
corresponding decrease in force.corresponding decrease in force.
8. 88
EF is between fulcrum and RF (load)EF is between fulcrum and RF (load)
Does not multiply forceDoes not multiply force
Resistance moves farther than Effort.Resistance moves farther than Effort.
Multiplies the distance the effort force travelsMultiplies the distance the effort force travels
9. 99
Wheel and AxleWheel and Axle
The wheel and axle is aThe wheel and axle is a
simple machinesimple machine
consisting of a largeconsisting of a large
wheel rigidly secured to awheel rigidly secured to a
smaller wheel or shaft,smaller wheel or shaft,
called an axle.called an axle.
When either the wheel orWhen either the wheel or
axle turns, the other partaxle turns, the other part
also turns. One fullalso turns. One full
revolution of either partrevolution of either part
causes one full revolutioncauses one full revolution
of the other part.of the other part.
10. 1010
PulleyPulley
A pulley consists of a grooved wheel thatA pulley consists of a grooved wheel that
turns freely in a frame called a block.turns freely in a frame called a block.
A pulley can be used to simply change theA pulley can be used to simply change the
direction of a force or to gain a mechanicaldirection of a force or to gain a mechanical
advantage, depending on how the pulley isadvantage, depending on how the pulley is
arranged.arranged.
A pulley is said to be aA pulley is said to be a fixed pulleyfixed pulley if it doesif it does
not rise or fall with the load being moved. Anot rise or fall with the load being moved. A
fixed pulley changes the direction of a force;fixed pulley changes the direction of a force;
however, it does not create a mechanicalhowever, it does not create a mechanical
advantage.advantage.
AA moveable pulleymoveable pulley rises and falls with therises and falls with the
load that is being moved. A single moveableload that is being moved. A single moveable
pulley creates a mechanical advantage;pulley creates a mechanical advantage;
however, it does not change the direction ofhowever, it does not change the direction of
a force.a force.
The mechanical advantage of a moveableThe mechanical advantage of a moveable
pulley is equal to the number of ropes thatpulley is equal to the number of ropes that
support the moveable pulley.support the moveable pulley.
11. 1111
Inclined PlaneInclined Plane
An inclined plane isAn inclined plane is
an even slopingan even sloping
surface. The inclinedsurface. The inclined
plane makes it easierplane makes it easier
to move a weight fromto move a weight from
a lower to highera lower to higher
elevation.elevation.
12. 1212
Inclined PlaneInclined Plane
The mechanicalThe mechanical
advantage of an inclinedadvantage of an inclined
plane is equal to theplane is equal to the
length of the slopelength of the slope
divided by the height ofdivided by the height of
the inclined plane.the inclined plane.
While the inclined planeWhile the inclined plane
produces a mechanicalproduces a mechanical
advantage, it does so byadvantage, it does so by
increasing the distanceincreasing the distance
through which the forcethrough which the force
must move.must move.
