1. Is The Hand Doing Work? 2B2 p 43

2. My hand has been exerting a force on the string to support the weight as the object is moving from A to B.
Has my hand done any work?

3. I now keep my hand at the same place and slowly pull in the string (twist over fingers) raising the object from D to C.
Has my hand done work in this case?

4. Which Way Should You Pull? 1C3 p 45

5. Which Way Should You Pull?
Fe on B
35N
What is the purpose of the pulley?

6. Gravity and Simple Pulley 1C1 p 51

7. When you let go of the two masses, what happens?
What did happen?
What is your explanation?

8. What is the Trade-Off for a Smaller Force (Pulleys)?
3B1 p 57

9. What is the Trade-Off for a Smaller Force
How much force does it take to slowly lift the mass?
We call this force the
weight
of the object.

10. Mount pulley to top support Fasten weight to other pulley
String the pulley
Hang weight to end of string
Add enough weight until the other weight rises
Measure din and dout
Record weightin and weightout
Fout
Fin
Fout
din
dout
Fin

11. Workin = Fin x din Workout = Fout x dout Ideal M.A. = din / dout
Actual M.A. = Fout / Fin
Efficiency = Wout / Win
Fout
Fin
Fout
din
dout
Fin

12. - Input Work = Input Force x Input Distance
Table 1
Input
Output
Mechanical
Situation
Force
Distance
Work
Advantage
Efficiency
(g)
(cm)
(g-cm)
  Actual | Ideal A | B C
- Input Work = Input Force x Input Distance
- Output Work = Output Force x Output Distance
How does the work output relate to the work input
- Mechanical Advantage Actual = Force Output / Force Input
- Mechanical Advantage Ideal = Distance Input / Distance Output
What does the mechanical advantage of a lever tell you?
- Efficiency = Work Output / Work Input
- Can you expect the efficiency of a machine to be over 100%?

13. What is the Trade-Off for a Smaller Force
How does the output distance compare to the input distance?
How does the output force, compare to the input force?

14. What is the Trade-Off for a Smaller Force
How does the output distance compare to the input distance?
How does the output force, compare to the input force?

15. MA = 1