1. Machines
A machine is a device with which you can do work in a way that is easier or more effective
A machine can be simple or complex
A machine makes work easier by:
Changing the amount of force you exert or
Changing the distance over which you exert the force
The direction in which you exert your force

2. Efficiency
Efficiency is the total work or energy input into a machine compared to the useful work or energy output of the machine
Output Work
Efficiency = x 100
Input Work

3. If there was no energy loss through friction or other causes, the efficiency of a machine would be 100%
No machine is 100% efficient, although some simple machines are very close to 100% efficient

4. Ideal Mechanical Advantage – the mechanical advantage of a machine if there was no friction. This can be calculated.
IMA = di/do
Actual Mechanical Advantage – the real mechanical advantage of a machine. This can be different for each machine and must be measured.
AMA = Fo/Fi

5. Part 2 – Simple Machines The 6 types of simple machines are:
The inclined plane
The wedge
The screw
The lever
The wheel and axle
The pulley

7. The Inclined Plane Mechanical advantage (MA)= output force/input force
Ideal MA = length of the incline/height of incline
If there was no friction the actual MA would equal ideal MA. In real life it is always less.
Incline length
Incline height

8. Wedge
A wedge is like a moving inclined plane to split or cut things apart.

9. Screw A screw is also related to the inclined plane.
The threads of a screw are like a spiral inclined plane.
The closer the threads, the greater the MA of the screw.

10. Levers (3 types) First Class Lever (a pry or seesaw)
Second class Lever (wheel barrel)
Third class Lever
(bat or ‘anything
that swings)
Output force
Input force
Input force
Output force
Input force
Output force
Distance from fulcrum to input force
Ideal MA =
Distance from fulcrum to output force

11. Wheel and Axle
The wheel and axle are fastened together so they rotate together (door knob, screw driver, steering wheel of a car)
radius of wheel(turn by you)
mechanical advantage = radius of axle (being turned)

12. Pulley A single fixed pulley has a mechanical advantage of one.
A single movable pulley has a mechanical advantage of two
We can add more movable pulleys to add more mechanical advantage.