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Tuesday, October 8, 2013

PHYSICS - SIMPLE MACHINES - II

Lever
     A lever is a simple machine made with a straight bar that moves on a fixed point called a fulcrum.  All levers have two parts, the bar and the fulcrum.  The longer the lever is, the less force will be needed to move the load. 
     The load and the force move in opposite directions.  Notice that as the hammer is pulled down, the nail moves up.

Examples of Levers
The tab is a lever used to
open the can.
The screwdriver is being
used as a lever.
The handle on the pump is
a lever.
The can opener is a lever.The bottle opener is a lever.The shovel is a lever.

Wheel and Axle
     A wheel and axle is made from a wheel that turns on a center post.  The larger the wheel is, the less force will be needed to move the load.  There are two parts to this simple machine, the wheel and the center post called the axle.
     The force moves in the same direction as the load.  Notice that in the picture, the force pushes in the same direction that the skateboard is moving.

Examples of Wheel and Axles

Skates use wheel and axles.

We use a wheel and axle to reel in the fishing line.

Wheelchairs use wheel and axles.

The knob part is the wheel.  The axle connects the two knobs.

The steering wheel is a wheel and the axle goes into the steering column.

Skateboards use wheel and axles.


Inclined Plane
     Any slanted surface is an inclined plane.  A ramp is the most common type.  A ramp is higher at one end than at the other.  The longer the inclined plane is, the less force will be needed to move the load.  The only part of an inclined plane is the slanted surface.  
     The load and the force move in the same direction.  Notice in the picture that the force is pushing the lawn mower in the same direction it is moving.

Examples of Inclined Planes

An inclined plane lifts the front of this car.

A long inclined plane equals the four steps.  The ramp goes up, turns and continues.

A short ramp is needed to equal these two steps.

Inclined planes make our work easier.

An inclined plane is used to lift this heavy wheelbarrow into this trailer.



Wedge
    A wedge is made by putting two inclined planes together.  They come together to form a V-shape.  A wedge may be used to lift or pry apart heavy objects.  A wedge can also be used to stop an object from moving.   A wedge has only one part. 
     The force and the load move in different directions.  In this picture, as the force moves the ax down, the load (wood) breaks apart and falls to the sides.

Examples of Wedges

The blade of a knife is a wedge.

Each blade of the scissors is a wedge.

The sharp edge of an ax is a wedge.
Shovel.jpg (15926 bytes)
The sharp edge of the shovel is a wedge.

A door stop is a wedge that stops the door from moving.

A wedge called a chock stops the car from moving.
Pulley
     A pulley is a wheel with a rope around it.  The rope fits into the groove on the wheel.  The larger the wheel is, the less force will be needed to move the load.  There are two parts to a pulley, the wheel and the rope. 
     The load and the force move in opposite directions.  As the rope is pulled down, the flag goes up.



Examples of Pulleys

Pulleys are used to open and close curtains and blinds.

A pulley is used to make this ladder longer.

A pulley is a grooved wheel with a rope around it.

Pulleys are used for exercise, especially in hospitals, to help patients grow stronger.

Pulleys are used to raise and lower sails on sailboats.

Pulleys are used to raise and lower flags.
Screw
     A screw is an inclined plane that is wrapped around a center post.  The longer the inclined plane is the closer the threads of the screw will be and the less force will be needed to move the load.  A screw has two parts, the inclined plane and the center post. 
     The force and the load move in the same direction.  As the force pushes down on the screw, the screw goes down into the wood.


Examples of Screws
Some screws have a sharp point and are mostly used on wood.
The faucet has threads to screw the hose on.
Some screws have a flat end.  We call these screws bolts.   Most bolts use a nut.

Many bottles and jars have screw on lids.

Bicycle tires have threads on the stem to screw the cap on.

Light bulbs have threads to screw them into sockets.





Add 3 or more simple machines in your notes from this module
draw, label & explain.  Use color!

DUE:  Wednesday 10/3