1. Topic 1.1 – Simple Machines
Levers

2. Way back when… The earliest machines were very simple devices.
Levers to pry rocks out of the ground
Ramps to help raise rocks as walls were built
The first machines all had something in common…
THEY ALL DEPENDED ON PEOPLE OR ANIMALS FOR THEIR SOURCE OF ENERGY

3. Roman Aqueducts
Thousands of years ago, Roman engineers developed a mechanical system for transporting water for many kilometers.
They were made of:
Pumps
Ramps
Distribution systems

4. Meeting the same need in different ways
Water is a NEED
Before we had taps with pumps like we do now, engineers used gravity to help move water through pipes.
A sakia was used
Had a series of buckets attached to long ropes which was draped over a wheel
Animals such as donkeys turned the wheel, raising the buckets of water

5. Archimedes does better
Archimedes invented a screw to help move water.
More efficient ways were always looked for
An Archimedes screw can move large amounts of water

6. Simple Machines
A simple machine is a tool or device made up of one simple machine
Lever
Inclined Plane
Wedge
Screw
Pulley
Wheel and Axle

7. Lever
A lever is a rigid bar or plank that can rotate around a fixed point called a fulcrum.

8. Levers are used to reduce the force needed to carry out tasks like:
Pulling nails
Opening bottles
Hitting a baseball
Cutting Paper
With a lever you can move a larger load than you could without using it.

9. Diagram
Effort Force
Load Force

10. 3 kinds of levers 1. First class lever 2. Second class lever
3. Third class lever

11. First Class Lever
A first class lever has the fulcrum between the load and the effort
pliers
Scissors
See-saw
Examples:

12. Second Class Levers
A second class lever has the load between the effort and the fulcrum
                         
Examples: Stapler
Wheelbarrow
Nut Cracker

13. Third Class Lever
A third class lever has the effort between the load and the fulcrum.
Examples:
Fishing rod
Tweezers

14. We build machines for two reasons:
1. To go faster or further
Distance/Speed Ratio
2. To make ourselves seem stronger or increase the amount of force we can apply
Mechanical advantage

15. Mechanical Advantage
A person on their own would never be able to lift a car.
A lever could make this possible!!!!
A scientific explanation for this is the lever provided mechanical advantage.

16. The mechanical advantage of a machine is the amount by which a machine can multiply a force
The force applied to the machine is called the input force
The force the machine applies to the object is called the output force
FORCES ARE MEASURED IN NEWTONS!

17. Mechanical Advantage (MA) = Output Force Input Force
If the Mechanical Advantage is:
Less than 1  The amount of force you are putting in is MORE than the force you are getting out.
Is equal to 1  The amount of force you are putting in is THE SAME AS the force you are getting out.
More than 1  The amount of force you are putting in is LESS than the force you are getting out.

18. Example:
If we had a first class lever that takes 45 N to lift a 45 N weight.
MA = 45N = N
This means, the amount of force you are putting in is the EXACT same as the force you are getting out.

19. If we had a first class lever that takes 45 N to lift a 180 N weight
MA = 180N = N
This means, the amount of force you are putting in is less than the force you are getting out.

20. If we had a first class lever that takes 180 N to lift a 45 N weight
MA = 45N = N
This means, the amount of force you are putting in is MORE than the force you are getting out. This is a bad mechanical advantage.