1. Machines!
U8D6,7

2. Catalyst – Monday 24th
1.) Name something that is not doing work. 2.) Susan walks up the stairs and then walks back down the stairs. Did she do work? 3.) A ball is kicked with a force of 15N and travels 3 meters, what work has been done on the ball? 4.) A car engine does 300J of work over 2 seconds. What is the power of that engine? 5.) A light bulb with 80w of power is on for 7 seconds. What work was done?

3. Catalyst – Monday 24th
1.) Name something that is not doing work. pushing down on a desk wile the desk is not moving. 2.) Susan walks up the stairs and then walks back down the stairs. Did she do work? YES!! 3.) A ball is kicked with a force of 15N and travels 3 meters, what work has been done on the ball? W = F x D = 15N(3m) = 45J 4.) A car engine does 300J of work over 2 seconds. What is the power of that engine? P = W/T = 300J/2s = 150w 5.) A light bulb with 80w of power is on for 7 seconds. What work was done? P = W/T => W = P x T = 80w(7s) = 560J

4. Agenda
(10) Catalyst & Answers (30) Simple Machine Notes (10) Simple Machine WS (25) Mechanical Advantage Notes (10) Mechanical Advantage WS (5) Exit Ticket

5. Essential Questions
1.) How do objects interact with each other? 2.) How does energy affect the motion of an object?

6. Why do we use Machines? Machines make work easier
A machine redistributes or redirects the force that we put into it.

7. Forces…AGAIN!!
There are two forces that are involved when machines do work.
(Fin) Input Force Output Force (Fout)
The force applies The force applied
to machine by machine

8. DRAW THIS!!!!!!
INPUT FORCE
OUTPUT FORCE

9. What is a simple machine? (video)
A simple machine is any device that only requires the application of a single force to do work
Makes work easier.

10. Types of Simple Machines
Please welcome The Lever Family!!!!! 1. The simple Lever 2. Pulley 3. Wheel & Axle

11. Levers A bar that is free to pivot around fixed point (fulcrum).
There are three classes of levers.

12. Levers
DRAW THIS!!!!!!
EXAMPLE: Seesaw
1st Class Lever: Fulcrum is between input force and output force.

13. Levers
DRAW THIS!!!!!!
EXAMPLE: WHEEL BARROW
2nd Class Lever: Output force is between fulcrum and input force.

14. Levers
DRAW THIS!!!!!!
EXAMPLE: LIFTING SOMETHING
3rd Class Lever: Input force is between fulcrum and output force.

15. Pulley
Grooved wheel with a rope, chain or cable running along the groove.
There are three different types of pulley systems.

16. Pulley
DRAW THIS!!!!!
Fixed Pulley: The wheel and axel of the pulley stays in one place.
Example: Flag pole.

17. Pulley
DRAW THIS!!!!!
Moveable Pulley: pulley that is free to move up and down, and is attached to a ceiling or other object by two lengths of the same rope.
Example: Construction Cranes & modern elevators.

18. Pulley
DRAW THIS!!!!!!
Block and Tackle: is a system of two or more pulley with a rope or cable threaded between them, usually used to. lift or pull heavy loads.

19. Wheel & Axle
Consists of an axle attached to the center of a larger wheel so that the wheel and axle rotate together.

20. Types of Simple Machines
Put your hands together for The Inclined Plane Family!!! 1. Simple inclined plane 2. Wedge 3. Screw

21. Inclined Plane
Sloping surface, such as a ramp that reduces the amount of force required to do work.
Example: Moving Ramp
Bob

22. The Screw
Inclined plane wrapped in a spiral around a cylindrical post.
Example: a screw

23. The Wedge An inclined plane with one or two sloping sides. Example:
Chopping
wood

24. Compound Machines Two or more simple machines that operate together.
Examples: Wheel barrow, escalator, scissors

25. Essential Question #1 How do objects interact with each other?
How can they interact with each other?

26. Essential Question #2 How does energy affect the motion of an object?
How does an object move? What do we have to do?

27. How much easier is the work?
Mechanical Advantage – How much easier and faster a machine makes your work
The mechanical advantage is the number of times a machine multiples your effort force.

28. Mechanical Advantage: Lever
MA = Fo (output force) / Fi (input force)
**On your reference table we will use the AMA formula.***

29. Example 1
The lever on the right has a Load of 30 N and is supported by a 10N effort. What is it’s mechanical advantage?
Which one is
Input? Output?
MA = 30N/10N
MA = 3

30. Example 2
Stephen pushes down with a force of 60N to lift a load of 300N off the ground. What is the mechanical advantage of the level?
What is the output
Force? Input?
300N/60N = Mechanical advantage is 5

31. Mechanical Advantage: Inclined Plane (Ramp)
MAramp = ramp length / ramp height
***On our reference table we will use the IMA formula for these problems.***

32. Example 1
A ramp has a slope length of 3,000 m to reach a height of 100m . What is the mechanical advantage of this ramp?
MA = length/height
MA = 3000m/100m
MA = 30

33. Example 2
A ramp is used to lift a heavy box up 9 meters. The ramp is 40 meters long. What is the mechanical advantage of using the ramp?
MA = 40m/9m
MA = 4.4

34. Mechanical Advantage: Pulley
MApulley = number of support ropes
What is the mechanical advantage of the pulley to the right?
1 MA

35. Example 1 What is the mechanical advantage of the pulley on the right?
What mass is the stick figure pulling? 4

36. A machine can never be 100% efficient because of : FRICTION
Efficiency
A measure of how much of the work put into a machine is changed into useful output work
Measured in percentages
A machine can never be 100% efficient because of : FRICTION

37. Efficiency Formula

38. Efficiency = Wout/Win x 100 Efficiency = 50J/100J = 0.5 x 100
Example 1
If a machine outputs 50 J of work and you input 100 J of work, what is the efficiency of the machine?
Efficiency = Wout/Win x 100
Efficiency = 50J/100J = 0.5 x 100
Efficiency = 50%

39. Example 2
A sailor uses a rope and an old, squeaky pulley to raise a sail that weighs 140N. He finds that he must do 180J of work on the rope in order to raise the sail by 1 m (doing 140 J of work on the sail). What is the efficiency of the pulley?

40. Exit Ticket Obj
1.) Describe what a simple machine is. What are its advantages? 2.) What is the mechanical advantage of a lever in which there was an output force of 90N and an input force of 15N? 3.) What type of pulley would have a greater mechanical advantage? 4.) If a machine outputs 150J of work and you have input 200J of work, what is the efficiency of the machine?