We've essentially finished the unit on Simple Machines. The Rube Goldberg project lies ahead, YEA! Starting Monday, bring in your supplies so you can start building it in class. Poster Board, Cardboard Boxes, Legos & Building blocks all make good support structures for your projects. The six simple machine to be included are as follows: Lever, Pulley, Inclined Plane, Wheel & Axle, Screw & the Wedge.
Now for some review. The essential idea in this unit was that simple machines make work easier by giving you a mechanical advantage. The trade off is Force for Distance. If you use less force, the effort travels a greater distance. Using the 4 different pulley systems we were able to measure both the force and the distance. We learned that it is a Reciprocal relationship. For example in our experiment we found that the number of ropes supporting the load determines how much effort is needed to lift the load. Two ropes requires half the effort, three ropes requires a third of the effort etc. We also found that when you use half the effort, the effort travels twice the distance(reciprocal), When you have three ropes supporting the load, you use one third the effort, but the effort travel three times as far. We can also predict the effort needed to lift a load without actually weighing it to find out. You divide the weight of the load by the number of ropes supporting the load. So, if we had a load of 120 pounds and a three rope pulley system( SFSM effort up), we would need 40 pounds of effort to lift the load.
Stay tuned for more details, review and information about our end of unit test. See you on Monday with your Rube Goldberg supplies.
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