Wednesday, May 15, 2013

Standard 21: Uses concepts of energy, work, and force to analyze systems such as simple and complex machines

The first concept to understand about how simple machines work is the formula work = force x distance . What this means is that if I need to get a certain amount of work done, but I have a limitation on how much force I can apply, I can make up for this discrepancy by increasing the distance I do. Simple machines let us do exactly that. The let us trade distance for force or force for distance. 
Picture a box that weights 200 pounds. Let's say I need to lift this box onto a platform that is 4 feet high. Now, being the skinny little kid that I am, there's no way I can accomplish this goal by just lifting it straight up. But, by introducing a ramp (an inclined plane) I can cheat the system. If I put in a long ramp that leads from the ground to the platform at an angle, I will increase the distance I have to go, say from 4 feet to 20 feet. But, because work = force x distance , I have just decreased the force I need to apply by the same ratio as distance added. Work smart, not hard, thanks to simple machines.


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