SIMPLE MACHINES AND MECHANICAL ADVANTAGE What is a

SIMPLE MACHINES AND MECHANICAL ADVANTAGE

What is a Machine? � Definition: �any device that makes work easier by changing a force � Work is done whenever a force moves an object over a distance

How do machines make work easier? � Machines change how the work is done by �Increasing the amount of force that is applied �Increasing the distance over which the force is applied �Changing the direction in which the force is applied

Increasing force? � The machine applies more force than the user but over a shorter distance

Increasing Distance � The machine increases the distance over which the force is applied, but it reduces the strength of the force

Changing the direction of force � The machine changes the direction of the force applied by the user

Simple vs. Compound Machines � There are 6 types of simple machines � Inclined plane � Lever � Pulley � Wheel and Axle � Screw � Wedge � Compound machines combine two or more simple machines

Measuring the change in force � How much a machine changes the input force is called its mechanical advantage � Remember �Input force = force you place on machine �Output force = force machine places on object � Two types: �Actual �Ideal

Actual Mechanical Advantage � Takes into account the amount of the input force that is used to overcome friction � Difficult to measure input and output forces

Ideal Mechanical Advantage � Uses input and output distance instead of force � Does not take into account friction and will always be greater than actual mechanical advantage

Practice Calculate the ideal mechanical advantage for the incline plane shown above.

Practice �A force of 200 N is applied to a machine in order to lift a 1, 000 N load. What is the mechanical advantage of the machine? �A machine is designed to push an object with a weight of 12 N. If the input force for the machine is set at 4 N, what is the mechanical advantage of the machine?

Practice � An input force of 35 N is applied to a machine with a mechanical advantage of 0. 75. What is the size of the load this machine could lift (how large is the output force)? � A machine is required to produce an output force of 600 N. If the machine has a mechanical advantage of 6, what input force must be applied to the machine?