Goal:
To create six simple machines, calculate their Mechanical Advantage (MA), Ideal Mechanical Advantage (IMA), and their Actual Mechanical Advantage (AMA).
Pulley
There are two kinds of pulleys, fixed and movable.
Fixed PulleyPulleys are probably the most hardest. This particular pulley is a fixed pulley. It is lifting up the weight with force on the opposite side as you can see in the picture. To find AMA you need to divide the resistance force by the effort force. To find IMA you will need to count the number of strings. In this case, the AMA is 1 and the IMA is also 1. To find the efficiency, you need to divide the AMA over the IMA which equals 100%.
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Movable PulleyThis is a movable pulley. This pulley can move up and down unlike the fixed pulley. It is of course harder to create and measure. The IMA is also found counting the number of strings. The load should always be split equally between ALL the strings. The same goes with AMA, it is resistance force divided by the effort force. To make an example, suppose the weight is 30 lbs. Add up the strings, there's 2 and divide it by 2. It would equal 15 for AMA. The IMA is 2. The overall efficiency is calculated the same way so it would be 100%.
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Levers
There are three different levers, first class, second class, and third class.
This first class lever is probably the most common one you see. When you think about this one you will probably be like everyone else and compare it to the see-saw. The effort force is on one end and the resistance is on the other end. To calculate AMA, you need to measure the effort force and the weight which is the resistance force. You then divide effort over resistance to find AMA. To get IMA you need to measure the distance between the effort force to the fulcrum. You would do the same with the resistance force. To get efficiency, you would need to divide the IMA over the AMA An example problem would be to find the AMA if the effort force is 20 and the resistance force is 100. Divide 100 by 20 and the AMA is 5. The mechanical advantage ob this class lever can be either <1 or >1.
Stepping up the difficulty a little, here is the 2nd class lever. The resistance force is in between the effort and the fulcrum. An example of this lever is a wheelbarrow. The load of the wheelbarrow represents the resistance force, the handles represent the effort force, and the wheel represents the fulcrum. To solve this problem, you will need to follow the same procedure that the first class lever, nothing is different in calculating AMA, IMA, and Efficiency. The MA of this lever will always be >1.
The third is probably the hardest one. It has the resistance on one end, the fulcrum on the other, and the effort in between. The best example for this one is a pair of tweezers. The resistance based on the end where you want to grab something with. The effort force is where you apply the effort to the tweezers in the middle. The fulcrum is where the the handles touch or come to connect.
Wheel and Axle
The wheel and axle is very similar to one of the levers. It resembles the first class lever with the fulcrum always in the middle. The resistance and the effort can be on the onside or the outside of the wheel. An example for a wheel and axle are the wheels on a car. To find AMA you take the resistance and divide it by the effort. If the resistance was 20 grams and the effort was 10 grams, the AMA would be 2. To calculate IMA you take the diameter of the resistance and divide it by the diameter of the effort. If the effort was 10in and the resistance was 2in then the IMA is 5. Divide AMA by IMA and you will get 2/5 which is 40% efficiency.
Inclined Plane
Inclined plane is probably the easiest to figure out in my opinion but you need to take it slow when figuring out the problem or one mess up can affect your whole problem. An inclined plane is a triangle with three different sized lengths.The resistance force is the height of the inclined plane, the effort force is the effort pushing the ball in the picture above. To find the IMA you will need to divide slope by height. If the slope were 12 and the height were 3, the IMA would be 4. For AMA it is the same equation as it has been before, Resistance force divided by effort force. The efficiency is AMA/IMA.
Screw
To find the AMA of this you need to find the resistance and divide it by the effort. The screw is the most widely known but the hardest and most complicated to calculate. Distance effort divided by distance resistance is how you find IMA.
Wedge
The final simple machine.... finally.
To calculate AMA of this you need to have the resistance force divided by the effort force. To get the IMA you'll need to know the distance traveled by the effort and the length of the wedge, by the distance traveled, or the height of the wedge. If the distance of the effort were 8 and the resistance distance was 2, the IMA would be 4. AMA is the same calculation that is repeated over and over again.