Question

Using a simple machine, a student is able to lift a 500N weight by applying only 100N. What is the mechanical advantage of the simple machine?

Answer 1

Mechanical Advantage is defined as the ratio of output force to the input force.
So in our question
\[F_{i} = 100 N\]
\[F_{o} = 500 N\]
So as per definition, Mechanical Advantage is
\[MA = \frac{ F_{o} }{ F_{i} } = \frac{ 500 N }{ 100 N } = 5\]

Answer 2

A couple of points. A simple machine doesn't have, as such, a power source. Unless, that is, you call the power the student is using to do the lift by whatever mean student is using. What I mean by power source is some form of fuel consuming engine.
Also, although it looks good that student can lift 500 N weight (50kg mass) using only 100N weight, (10kg mass), the actual DISTANCE student will be able to lift the mass is smaller than the distance that the student will have to move to do so. Think of a "see saw" with a pivot. Having the 500N close to one side of the pivot, and student sitting a long way away from the other side of the pivot, gives student what you may know as "leverage". The student will travel a lot further down than the weight being lifted travels up. All of which could be a long winded way of saying that you don't get "something for nothing".
Good things machines, and when a machine is actually connected to an engine, well, welcome to the motorway !

Answer 3

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