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# Levers

By: Bradley Dover, Nick Fornek, Noah Davis, Ben Kilpatrick, Tucker Ramey
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on 26 September 2012

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#### Transcript of Levers

Levers By: Lever- A rigid bar resting on a pivot, usually used to help move a heavy or firmly fixed load with one end when pressure is applied to the other. Function MA Length of the resistance arm Length of the effort arm 1st Class Efficiency Mechanical advantage(MA) Velocity Ratio (VR) Distance moved by effort Distance moved by load VR= 100% . Simple Levers 1st Class : Crowbar
2nd Class : Wheelbarrow
3rd Class : Baseball bat 2nd Class
Increases force, but not direction

3rd Class
Increases distance, but not direction Function Effort Load The efficiency is NEVER 100% because of outside forces like gravity and friction. or Force of resistance Force of effort Effort Load Effort Load The End Compound Levers 1st : Nail Clippers
2nd : Nutcracker
3rd : Chop Sticks Let's say Philip has a can of baked beans. He wants to use a flat-head screwdriver to open it. If he positions the screwdriver so that 5 cm of the screwdriver is inside the can, and 10 cm of the screwdriver is outside the can, what will be the mechanical advantage of using the screwdriver. A man pushes a wheelbarrow on a flat area. The bagels in the wheelbarrow weighs 30 N, and he can lift the wheelbarrow using 10 N of force. What is the mechanical advantage? Another Example ANSWER To solve for MA, we need either effort and resistance's distance from the fulcrum, or the effort and resistance's forces. We know from the problem the distances that the effort and resistances are from the fulcrum, so we will use the method involving the distances. The length of the effort bar is 10 cm, and the length of the resistance bar is 5 cm. Using the formula you divide the effort bar's length (10 cm) by the resistance bar's length (5 cm) which gives you 2. The mechanical advantage of using a screwdriver to open the can is 2. The same rules apply here except that we are using the force method and not the distance method. The resistance, or the bagels, weigh 30 N and the effort, or the force he uses to lift it, is 10 N. So if you put that into the formula, the force of resistance (30 N) divided by the force of resistance (10 N), you get 3. The mechanical advantage of using the wheelbarrow is 3. Bradley Dover Nick Fornek Tucker Ramey Ben Kilpatrick Noah Davis Changes direction of input force If fulcrum is closer to output force, it increases force. If it's closer to input, it increases distance
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