Simple Machines
November 24th-25th
S
Goal:
S I will be able to explain the relationship
between mass, force and distance
traveled.
S I will be able to describe the difference
between different simple machines.
What makes something a simple
machine?
S Simple machines make work easier! A
simple machine has few or no moving
parts.
S Simple machines make work easier by
changing the amount of force applied,
the direction of the force or both.
What exactly is work?
S Work is done when a force moves an object over a distance.
S Work requires movement of an object so if you push the
desk and it does not move even though you are putting in a
great deal of effort and applying force no work has been
done.
Graphic Organizer
S We will need 7 pieces of paper
S We are going to make a flip chart to record the different
kinds of simple machines.
Bill Nye: simple machines
levers!
S http://www.neok12.com/video/Simple-
Machines/zX7a7d457d065b790405707f.htm
Levers
S Rigid bars that pivot around a point
S Change the direction of the force, change the ratio of the
force and the distance an object move or both.
Types of Levers
S First Class:
the fulcrum is between the effort ( the force that is applied to
the lever) and the load (the force that works against the effort)
Examples include: seesaws, crowbars, and fingernail
clippers
Second Class Levers
S The load is placed between the fulcrum and the effort force.
S The lever increases the force but does not change its
direction
S Examples: wheelbarrows, nutcrackers
Third Class Levers
S The effort is applied between the fulcrum and the load.
This is the only type of lever that always reduces the effort
force instead of increasing it.
S Examples: chopsticks, fishing rod, shovel, stapler, tweezers
Wheel and Axels
S The wheel and axel started being used around 3300 BC.
S Changes the amount of force applied to an object.
S Used to steep a struck, open a valve on a water pipe, seal a
submarine hatch.
S The wider the wheel the less effort it takes to turn it. This also
means that you will need to turn the wider wheel a greater
distance to do the same amount of work.
Wheel and axel
Pulleys
S A pulley is a wheel with a groove along its edge.
S A single fixed pulley consists of a pulley attached to a high
point, with a rope fed through the wheel groove. It is called
a fixed pulley because the pulley remains in place.
S Fixed Pulley: Changes the direction of the force needed to
move an object, but not the amount of force needed.
Pulley System
S Combine two or more pulleys together. The more ropes
supporting the load the less force you need to lift the load
and the more rope you need to pull through.
pulleys
https://www.youtube.com/watch?v=LiarGb
_LK10
Brain Pop Videos on Pulleys,
wheel and axels, and levers
S Levers:
https://www.brainpop.com/technology/simplemachines/levers/
S Wheel and Axels:
https://www.brainpop.com/technology/simplemachines/wheelanda
xle/
S Pulleys:
https://www.brainpop.com/technology/simplemachines/pulley/
Workbook Pages
Pages: 228-232
Inclined Planes
S Decreases the amount of force required to raise an object.
S Why use an inclined plane?
S By pushing the object on an angle, the force needed to oppose
gravity is less.
Inclined planes
https://www.youtube.com/watch?v=Zj_iWi
XUZX8
Wedges and Screws
S A wedge is a simple machine that consists of two inclined
planes back to back.
S A wedge changes the direction of the force.
S A screw is an incline plane wrapped around a cylinder or
cone. The screw changes both the direction of the force and
the ratio of the force
Wedge
http://mocomi.com/wedge/
Screw
https://www.youtube.com/watch?v=dDEhr
pFb1BU&src_vid=4oPPQpF7bHY&feature=
iv&annotation_id=annotation_2624978011
Car jacks are an example
Light bulbs screw into lamps
Toothpaste caps
Jar lids
Compound machines
S Tools that are made of a combination of simple machines
are called compound machines.
S Scissors: pair of levers with a fulcrum in the middle and the
blade is a wedge.
S Bicycle: pedals are levers and the sprocket is a wheel and
axle
Compound machines
Workbook Pages
SPages: 233-235