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# Lever lab

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### Lever lab

1. 1. Lever Lab Lab Activity! If you do not have your Lab Safety Contract signed and returned, you may not participate.
2. 2. BrainPop - Levers
3. 3. Materials • • • • • A #2 yellow pencil, A ruler. 5 nickels 20 pennies Masking tape
4. 4. Background (Research) • In science, a force is a push or a pull that causes an object to change its speed and/or direction. If a car stalls and must be pushed off the road, the person pushing it does a great deal of work! • Work is the force used to push or pull an object multiplied by the distance the object travels in the direction of the applied force. W=FXD Work = Force X Distance
5. 5. Background (Research) • Work is what happens when a force causes an object to move. • Work is calculated by multiplying force X distance: W = F X D. • To change the amount of work done, either the force must change, the distance must change, or both.
6. 6. Background (Research) • A lever is a rigid bar that rests on and pivots around a fixed point called a fulcrum. • Levers can increase the effort force and can change the direction of force. • If we apply a push or a pull to one end of the lever the other end of the lever will go in the opposite direction
7. 7. Purpose To demonstrate basic relationships between force and motion using a lever. Question Write a research question for this investigation: How does ______________ effect ___________________? ~ or ~ What is the affect of _____________ on ______________?
8. 8. Experiment, Part I Procedure • Tape a pencil to the top of your table or desk. • Balance a ruler on top of and perpendicular to the pencil. • Make a labeled drawing showing a side view of the setup in your journal. Label the lever and the fulcrum. • We will label the load, and where you would apply the effort force to make the load move upward in a few minutes.
9. 9. Experiment, Part I Procedure • Make a labeled drawing showing a side view of the setup in your journal. Label the lever and the fulcrum. • We will label the load, and where you would apply the effort force to make the load move upward in a few minutes. lever fulcrum
10. 10. Experiment, Part I Procedure • Explain what you have to do to get the ruler to balance on top of the pencil.
11. 11. Experiment, Part I Procedure • Predict everything that will happen if you place a nickel on the zero end of the ruler.
12. 12. Experiment, Part I Procedure • Predict everything that will happen if you place a nickel on the zero end of the ruler. • Write a hypothesis using your prediction . Write a hypothesis using an If, Then statement that shows how you think the independent variable will affect the dependent variable. If _____________, then _______________.
13. 13. Experiment, Part I Procedure • Place the nickel on the zero end of the ruler. Was your prediction correct? Did you leave anything out? If so, add it to your journal entry. • Explain why the “zero” end of the ruler moved downward.
14. 14. Experiment, Part I Procedure • Place the nickel on the zero end of the ruler. Was your prediction correct? Did you leave anything out? If so, add it to your journal entry. • Explain why the “zero” end of the ruler moved downward. • What is the name of the system you just made? Without moving the nickel or the pencil, what can you do to make the “zero” end of the ruler move upward?
15. 15. Experiment, Part I Procedure • Finish labeling your drawing showing the side view of the parts of your system. • Label the lever, the fulcrum, the load, and where you would apply the effort force to make the load move upward. effort load lever fulcrum force
16. 16. Experiment, Part I Procedure • Use pennies as your effort force. How many pennies of effort force does it take to move the load of one nickel? • Record your results, on the table. • How many pennies of effort force does it take to move the of 2, 3, 4, and 5 nickels? • Record your results.
17. 17. Experiment, Part I Procedure Load or Resistance Force (# of nickels) Effort Force (# of pennies) 1 2 2 3 4 5
18. 18. Experiment, Part I Procedure • Predict the effort force needed to lift 10 nickels. Describe the method you used to make your prediction. • Describe the method you used to make your prediction. Use complete thoughts and sentences.
19. 19. Experiment, Part I Variables • What is the independent variable in this question? ____________________________ • What is the dependent variable in this question? ____________________________ • What FACTORS did you hold constant so that your testing would be fair? ____________________________
20. 20. Experiment, Part II Procedure • In the two diagrams below, the fulcrum is placed at the center of each ruler. • Compare the distances (d) in the two setups. Load Effort force d table Load Effort force d table
21. 21. Experiment, Part II Procedure • Use the same materials as in Part I; however, change the setup so that the fulcrum or pencil is placed at the 10 cm mark instead of in the center of the ruler. • Make a labeled drawing showing a side view of the setup in your journal. Label the lever, the fulcrum, the load, and where you would apply the effort force to make the load move upward.
22. 22. Experiment, Part II Procedure • Make a labeled drawing showing a side view of the setup in your journal. Label the lever, the fulcrum, the load, and where you would apply the effort force to make the load move upward.
23. 23. Experiment, Part II Procedure • Fill in the table like the one in part 1. Load or Resistance Force (# of nickels) Effort Force (# of pennies) 1 2 3 4 5 • What is the relationship between the effort force needed to lift the nickel and the distance the fulcrum is located from the load?
24. 24. Analysis Study the diagram. Write a statement that compares the distance the load moves versus the distance effort force must be applied to lift the load. Distance load is moved d d Distance effort force is applied
25. 25. Answer: When you move the fulcrum farther away from the effort force and closer to the load, you are pushing on the long end of the lever, so it requires less effort force to lift. With levers, distance and effort are related. If you increase the distance over which you exert the force, then you can decrease the that force and still get the job done.
26. 26. Analysis Remember, a simple machine such as a lever does not change the amount of work that must be done. The machine simply provides a tradeoff of effort force versus distance. Since work is a mathematical product of force times distance, if the force decreases, then the distance must increase. On the other hand, if the force increases, then the distance must decrease. Work = f d Work = f d Distance load is moved d d Distance effort force is applied
27. 27. Conclusion On the back of your lab paper, answer the following question. Please RESTATE and answer in complete thoughts and sentences. If you want to use a lever to lift a load, where will you place the load and the fulcrum so that you use the least amount of effort force?