1. Using Machines

2. What is a machine?
All machines make tasks easier, but they do not decrease the amount of work required.
A machine changes the way in which work is done.

3. How do machines make work easier?
Machines make work easier in 3 ways.
1. the size of a force
2. the distance the force acts
3. the direction of a force

4. Change the Size of a Force
Could you pull a nail out of a board with only your hands? A hammer makes the work easier by increasing the output force over a shorter distance.
When an output force is greater than the input force, the output force acts over a shorter distance.

5. Change the Distance a Force Acts
Using a rake to gather leaves is an example of a machine that increases the distance over which a force acts. Your hands move the rake over a short distance, however the other end sweeps through a greater distance making it easier to rake leaves.
When the output force acts over a longer distance than the input force, the output force is less than the input force.

6. Change the Direction of a Force
Using a pulley and a rope changes the direction of lifting an object. The machine changes the direction of the applied force.
Equal output and input forces act over equal distances.

7. What is Mechanical Advantage?
A machine’s mechanical advantage(MA) is the ratio of a machine’s output force produced to the input force applied.
Ideal mechanical advantage(IMA) is the mechanical advantage if no friction existed.

8. What is Efficiency?
The output work done by a machine never exceeds the input work of the machine because of friction. Friction converts some input work to thermal energy which cannot be used to do work.
The efficiency of a machine is the ratio of the output work to the input work. Because of friction, the machine’s efficiency is always less than 100%. Lubricating a machine’s moving parts increases efficiency.