1. Do Now: 02/19/2014
What type of simple machines are shown below:

2. Objectives Learning Intentions – Success Criteria –
Students will be able to explain how machines work based on the concept of mechanical advantage
Success Criteria –
We will know we are successful when we can accurately calculate the mechanical advantage of a machine

3. Mechanical advantage
Mechanical advantage is the ratio of output force to input force.
MA = Output force (N) ÷ Input force (N)

5. The Lever
Levers are useful because you can arrange the fulcrum and the input arm and output arm to adjust the mechanical advantage of the lever.

6. Other forms of Equation
Mechanical Advantage of lever = length of input arm ÷ length of output arm

7. Ramps
A ramp is a simple machine that allows you to raise a heavy object with less force than you would need to lift it straight up.
The mechanical advantage of a ramp = ramp length ÷ height of the ramp.

8. Solving Problems
A crowbar is a type of lever that you use to pull a nail out of a piece of wood.
If the handle of a crowbar is 40 centimeters and the foot is 2 centimeters, what is its mechanical advantage?

9. Practice Problem:
A construction worker uses a board and log as a lever to lift a heavy rock. If the input arm is 3 meters long and the output arm is meters long, what is the mechanical advantage of the lever?

10. Practice Problem
A 500-newton cart is lifted to a height of 1 meter using a 10-meter long ramp. You can see that a worker only has to use 50 newtons of force to pull the cart.

11. Independent Practice:
Complete the remaining practice problems on your own or with a partner
Completed sheet should be in your folder for folder checks

12. Do Now: 02/20/2014
A machine has an input force of 100 newtons to produce an output force of 25. What is the mechanical advantage of this machine?
A 10 meter ramp lifts an object to a height of 2 meters. What is the mechanical advantage of the ramp?

13. Objectives: Learning Intentions Success Criteria
Students will be able to explain major concepts from the unit
Success Criteria
We will know we are successful when we can accurately complete the review packet demonstrating knowledge from the unit

14. TERMS Work – the amount of force applied to an object over a distance
Object must MOVE for work to be done
Power – the rate at which work is done
Amount of work done in a given time
Efficiency – the ratio of usable output work divided by total input work for a machine

15. TERMS Energy – the ability to do work
Potential Energy – energy of position
Stored energy
Depends on mass and height
Kinetic Energy – energy of motion or movement
Depends on mass and speed

16. BUT THE TOTAL AMOUNT OF ENERGY REMAINS THE SAME!
Terms
Conservation of Energy: The idea that energy transforms from one form into another without a change in the total amount
Potential Energy can transform into kinetic energy;
Kinetic Energy can transform into potential energy;
BUT THE TOTAL AMOUNT OF ENERGY REMAINS THE SAME!

17. TERMS
Machine – is a device with moving parts that work together to accomplish a task
Input – everything you do to make a machine work
Output – what the machine does for you
Simple Machines – unpowered mechanical device

18. 6 Types of Simple Machines
Lever
Gears
Ropes and Pulleys
Wheel and Axle
Ramp
Wedge

19. MA = Output force (N) ÷ Input force (N)
Mechanical Advantage
In general, Mechanical advantage is the ratio of output force to input force:
MA = Output force (N) ÷ Input force (N)
Special Cases of Mechanical Advantage:
Mechanical Advantage of a Lever =
length of input arm ÷ length of output arm
Mechanical Advantage of a Ramp =
Ramp length ÷ Height of ramp
Note that Mechanical Advantage has no units!

20. Review of Equations: Work = force X distance Power = work ÷ time
Force = work ÷ distance
Distance = work ÷ force
Power = work ÷ time
Work = power X time
Time = work ÷ power

21. EQUATIONS Potential energy = weight X height
Potential Energy (PE) = Mass X Gravity X Height
Mass measured in kg
Gravity = 9.8 m/s2
Height measured in meters
Potential energy = weight X height
REMINDER: Weight = mass X gravity
Kinetic Energy (KE) = ½(mass)(velocity)2

22. EQUATIONS
MA = Output force (N) ÷ Input force (N)

23. UNITS Distance: ___________ Time:___________ Force: ______________
Work: _____________
Power: ____________
Energy: _____________
Mechanical Advantage: ____________

24. PRACTICE!
Complete the practice problems – problems are similar to the ones on your test tomorrow
Questions – ASK TODAY!

25. Do Now: 02/21/2014 Take out your review packet from yesterday
Any questions before we start the test?

26. TEST!
Complete independently – if you are talking or out of your seat I will think you are cheating!
If caught cheating – you will receive a zero until you can come and make up the test on your own time!
Finished – tell me what you know about waves!