Simple Machinesthe six types of simple machines are the lever, wheel and axle, inclined plane, wedge, screw, and pulley

Simple Machines

A machine is something that makes work easier by changing the size of a force needed, the direction of the force needed, or the distance over which a force acts.

Lever

lever – a bar that rotates at a fixed point (called a fulcrum)

Examples - ????

Levers

Three “classes” of levers

1st Class

2nd Class

3rd Class

Wheel & Axel

wheel & axel – two round objects that move together. The larger object is the wheel and the smaller the axel.

Example - ????

Pulley

Pulley – consists of a rope that fits into a groove in a wheel.

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Pulleys

Fixed Pulley

Movable Pulley

Pulley System

Simple Machines

A machine is something that makes work easier by changing the size of a force needed, the direction of the force needed, or the distance over which a force acts.

Work

Machines do not decrease the amount of work, they lower the force that is needed to do the same work by increasing the distance the force is applied.

Work – the product of force and distance

Work is done when a force acts on the object in the direction the object moves.

Answer this…..

A person lifts a box.

Was work done to the box?

A person carries a box from one table to another.

Was work done to the box?

Work being done?

For a force to do work on an object, some of the force must act in the same direction as the object moves. If there is no movement, no work is done.

Any part of a force that does not act in the direction of motion does no work on an object.

examples of Work

w = F xd

work = applied force x distance

How much work is done if you push a chair that weighs 60 N across a room for 5 m?

w = F xd

w = 60 N x 5 m

w = 300 J