1. SIMPLE MACHINES
Chapter 5 Notes

2. Machine A device that helps make work easier
Changes the size or direction of the force
Simple Machine – A type of machine that uses only one kind of motion to make work easier
Complex Machine – a combination of simple machines.

3. Six Simple Machines
1. Lever – a bar that pivots around a fixed point (fulcrum)
1st Class – the fulcrum in between the input force and output force
input
output
fulcrum

4. Levers continue:
2nd Class – the output force is between the fulcrum and the input force.
3rd Class – the input force is between the fulcrum and the output force
output
input
fulcrum
fulcrum
input
output

5. Force Distance Trade Off
What increases for work input must decrease for work output.
As force increases, distance decreases.
As force decreases, distance increases.

6. Mechanical Advantage How much force a machine is applying for you.
MA = Output Force ÷ Input force
The larger the mechanical advantage, the easier a machine makes your work.

7. Mechanical Efficiency
Measures how much friction a machine has. More Friction equals less work output.
ME = (work output ÷ work input) 100
Measured as a percentage

8. Simple machines 2. Inclined Plane – ramp ( forms a right angle)
Applies a smaller force over a longer distance

9. Simple Machines 3. Wedge – A double inclined plane
Ex: knife, doorstop, ax head

10. Simple Machines
4. Screw – an inclined plane, wrapped around a cylinder
5. Wheel and Axle – a simple machine with two circular objects of different sizes.
Wheels with teeth

11. Simple Machine 6. Pulley – a grooved wheel that holds a cable.
Fixed Pulley – the pulley is attached and changes the direction of the force only
Movable – increases force without changing direction
Block and Tackle – A fixed pulley and a movable pulley are used together for a greater mechanical advantage