PRESENTATION OUTLINE
Pulley
a wheel with a groove that holds a rope or chain
Since pulleys are potent contraptions they can help us by changing the direction of a force, which can make it much easier for us to move something.
Lever
a rigid bar that pivots about one point and that is used to move an object at a second point by a force applied at a third.
like all simple machines, the lever helps by making doing work easier by reducing the force needed to move an object. In order to reduce the force needed, the distance over which the force is applied must be increased.
Wheel and axle
a simple lifting machine consisting of a rope that unwinds from a wheel onto a cylindrical drum or shaft joined to the wheel to provide mechanical advantage.
a wheel and axle makes work easier for us by changing the amount of force applied to a load. The object that is being moved is a load located at the axle. A force applied at the outer edge of the wheel moves the load.
Screw
is a mechanism that converts rotational motion to linear motion, and a torque (rotational force) to a linear force
Screws have a corkscrew-shaped ridge, known as a thread, wrapped around a cylinder. The head is specially shaped to allow a screwdriver or wrench to grip the screw when driving it in. The most common uses of screws are to hold objects together — such as wood — and to position objects.
Inclined plane
a sloping ramp up which heavy loads can be raised by ropes or chains.
And inclined planes make it easier to lift something heavy, like a rock. Instead of lifting the rock straight up, you can push it a greater distance, but with less force. The amount of work remains the same
Wedge
a piece of hard material with two principal faces meeting in a sharply acute angle, for raising, holding, or splitting objects by applying a pounding or driving force, as from a hammer.
wedge utilizes a principle known as mechanical advantage in order to reduce the force needed to lift or separate an object. When driven under load, wedges function by transferring the direction of force applied.
Mechanical advantage a factor by which a machine multiplies the effort force
Lever
First class
Second class
Third class
Inclined plane family
Wedge
Screw
Compound machine
A machine consisting of two or more simple machines operating together, as a wheelbarrow consisting of a lever, axle, and wheel.
Simple machine
A tool with few parts that makes it easier or possible to do work
Pulleys
Fixed pulley
Moveable pulley
Inclined plane family
Wedge
Screw
