Simple Machines and Levers

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Machines Lab

It’s Not Elven Magic!

Introduction and Theory

“One machine can do the work of fifty ordinary men. No machine can do the work of one extraordinary man” –Elbert Hubbard1. Machines often are used to make life easier for human beings. A simple machine is described as a device used when a fore is being applied to an object. Simple machines include: levers, pulleys, wheel and axle, gears, inclined plane, wedge, and screws. Complex machines are systems of simple machines used together to get work done.

Mechanical advantage is how much input work is applied to machine compared to the output force put out by the machine. The mechanical advantage calculated by taking the actual measurements of the machine, such as length and height and displacement, is the ideal mechanical advantage or IMA. The mechanical advantage of a machine is calculated using the actual forces applied to the machine and force output from the machine. This is called the actual mechanical advantage or AMA. The AMA of a machine is always less than the IMA because of friction. Friction opposes the input forcing you to input more force than the calculated amount in the IMA calculation.

There are many reasons to use machines. Some simple machines change the direction of input force, multiply force, or multiply speed and displacement. You can tell if the machine is a force multiplier or a speed and displacement multiplier by looking at the calculated IMA. If a machine has a mechanical advantage >1 than it is a force multiplier. If a machine has a mechanical advantage <1 then it is considered a speed/displacement multiplier. If a machine has a mechanical advantage = 1 then it is most likely to be used to change the direction of the input force applied t...

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...rove everyday life whether we recognize it or not. We saw many patterns during this lab such as the fact that AMA was most commonly around 70% of the IMA, meaning that the efficiency was always around 70% except for the wheel and axle which makes sense because wheels are meant to reduce friction which mainly causes a loss in efficiency.

This lab was a very effective lab in changing my outlook on most things in life. This lab makes me realize that almost everything I do involves a simple machine whether it’s my body or a machine system I am using. Machines are very important for the regular function of everyday life. This was definitely one of the most influential teaching experiences I faced in my academic career for these reasons.

Citations

1 http://www.brainyquote.com/quotes/keywords/machine.html

2 http://iqa.evergreenps.org/science/phy_science/ma.html