Machines 4. Simple Machines
Simple Machines http://atlantis.coe.uh.edu/archive/science/science_lessons/scienceles1/finalhome.htm
There are thousands of different kinds of machines You use machines every day
A device that makes work easier But did you know that all machines are based on only six (6) kinds of simple machines Vocabulary: Simple machines A device that makes work easier
A lever is one type of simple machine Vocabulary: lever A rod that can turn on a point called a fulcrum
A point on which a lever can turn Vocabulary: fulcrum A point on which a lever can turn
If you push down on the end of one kind of lever The other end moves up
You can lift things more easily because less force is needed
There are three (3) basic kinds of levers They are different because each kind has the fulcrum in a different place
The fulcrum is between the load force and the effort force First class lever: The fulcrum is between the load force and the effort force
The load force is between the effort force and the fulcrum Second class lever: The load force is between the effort force and the fulcrum
The effort force is between the fulcrum and the load force Third class lever: The effort force is between the fulcrum and the load force http://www.worsleyschool.net/science/files/lever/quiz.html
An inclined plane is a flat surface that slopes Vocabulary: Inclined plane A flat surface that slopes
A board from a low place to a high place is an inclined plane called a ramp
Less force is needed to slide an object up a ramp than to lift the object
A wedge can split a log more easily by hitting a wedge stuck in the log
Two inclined planes that come together at a point Vocabulary: wedge Two inclined planes that come together at a point
A screw is an inclined plane wrapped around a rod Screws hold things together better than nails
You can fasten an object to one end of the rope on a pulley If you pull the other end, you can lift the object
A wheel with a rope around it and is used to lift objects Vocabulary: pulley A wheel with a rope around it and is used to lift objects
3 Basic Types of Pulleys: Fixed Pulley Mechanical Advantage is 1 If you are lifting 150 pounds you have to apply 150 pounds force
Mechanical Advantage: Count number of rope sections NOTE: Subtract 1 if you have to pull down on rope 2 ropes pieces 1 you use to pull down to apply force Mechanical Advantage: 1
Mechanical Advantage is 2 Moveable Pulley Mechanical Advantage is 2 If you are lifting 150 pounds you have to apply 75 pounds force
Combined Pulley Mechanical Advantage is 2 Count number of rope pieces Subtract 1 since pulling down Mechanical Advantage is 2 If you are lifting 150 pounds you have to apply 75 pounds force
Combined Pulley Mechanical Advantage is 3 Count number of rope pieces Pulling up so it counts Mechanical Advantage is 3 If you are lifting 150 pounds you have to apply 50 pounds force
Several pulleys can be joined together Count number of rope pieces Subtract 1 since pulling down Mechanical Advantage is 3 to make it easy to lift heavy objects
Identify the mechanical advantage in each set of pulleys: MA ? MA ? MA ?
A wheel and axle is really a kind of lever that continues to turn around its fulcrum