Act7_sol - Per 7 Activity Sheet Solutions: Simple Machines...

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25 50 cm 5 N Per 7 Activity Sheet Solutions: Simple Machines 7.1 How do Levers Work? – Fulcrums and Forces a) Place a meter stick on the plastic tube with the 50 cm mark directly above the tube. Place a 5 newton weight at the 100 cm mark of the meter stick. Raise the weight by pressing down on the other end of the meter stick with your finger. Now move your finger closer to the center of the meter stick and press down again. What happens to the amount of force needed to raise the weight as your finger moves closer to the 50 cm mark? ? _ The amount of force you must apply increases as you press closer to the center of the lever._ b) Your instructor will demonstrate the force and fulcrum board. 1) Describe what happens when the fulcrum is placed under the center of mass of the board and one weight is placed on each end. The two ends of the board are approximately level. 2) What happens when two weights are placed at one end and one weight is placed at the other end? The end of the lever with one weight is raised and the end with two weights is lowered. 3) What should be done to the fulcrum so that one weight on one end can lift two weights on the other end? The fulcrum must be placed near the end with two weights so that the lever arm is longer than the load arm. 7.2 How Do We Use Levers? a) Examine the examples of levers (scissors, hammer, grass clippers, pliers, nutcracker, can opener, etc.). Make a rough sketch of one of these tools and label the fulcrum, lever arm, and load arm. b) Explain how this tool uses levers to trade force for distance. Tools with long lever arms and short load arms, such as pliers, trade a small force in over long lever arms for a large force out over short load arms. Tools with short lever arms and long load arms, such as grass clippers, trade a large force in over short lever arms for a small force out over long load arms. Load Arms Fulcrum Lever Arms
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26 c) The red hinged board represents a human arm. The hinge represents the elbow, and the spring scale represents a muscle. 1)
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This note was uploaded on 06/11/2011 for the course PHYSICS 103 taught by Professor Staff during the Spring '10 term at Ohio State.

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Act7_sol - Per 7 Activity Sheet Solutions: Simple Machines...

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