1. Work & Mechanical Advantage
Simple Machines
Work & Mechanical Advantage
By PresenterMedia.com

2. Work Recap: Work is measured in Joules (J)
Work is done when a force is applied to move an object through a distance.
Work is measured in Joules (J)
Force is measured in Newtons (N)
Distance is measured in meters (m)
The formula to calculate work is:

3. Work
Example #1: Lisa pushes a shopping cart 100m using a force of 75N. How much work has Lisa done?

4. Work
Now you try!
Example #2: Tom kicks a soccer ball with a force of 150N and the ball travels 25m. How much work has Tom done?

5. Work and Simple Machines
Remember:
Simple machines can make work easier by decreasing the force required.
The trade-off is that the force must be applied through a greater distance.
Force
Distance

6. Work and Simple Machines
Example: A force of 10N must be applied to lift a box to a height of 12m. A force of 4N is needed to move the box up an inclined plane with a length of 30m. Calculate the work done with and without the inclined plane.
F=4N
d=30m
F=10N
d=12m
Work is the same!

7. Mechanical Advantage
The mechanical advantage (MA) of a simple machine is the relationship between the force required to move a load without a simple machine and the force required to move the same load with a simple machine.
The mechanical advantage of a simple machine can be calculated using the following formula:
Where:
Load = the force required without a simple machine
Effort = the force required using a simple machine

8. Mechanical Advantage
Example #1: A force of 10N is required to move a box. Using an inclined plane, the force required to move the same box to the same position is 4N. What is the MA of the inclined plane?
This means that 2.5 times less force is needed to move the box using the inclined plane.
The work is 2.5 times easier.

9. Mechanical Advantage Now you try!
Example #2: A force of 500N is required to lift a heavy bucket to a height of 5m. Using a lever, the force required to lift the same bucket to the same height is 125N. What is the MA of the lever?

10. Mechanical Advantage
Both a first and second class lever have a mechanical advantage greater than 1.
This means that less effort is needed to move a load making it easier to do the work.
A third class lever has a mechanical advantage less than 1.
This means that more effort is needed to move a load making it harder to do the work.
THERE IS NO MECHANICAL ADVANTAGE!