Mechanical Advantage vs. Efficiency: What's the Difference?

http://en.wikipedia.org/wiki/Mechanical_advantage

http://en.wikipedia.org/wiki/Efficiency

They are nothing to do with eachother. The mecahanical advantage of say a simple lever would be calculated from the distances between load and fulcrom and effort and fulcrum. The efficience would just depend on how much the lever flexed , how much friction was in the fulcrum, how effectively the load was connected to the lever.

So one is to do with the theoretical advantage * gained by the levers pulleys etc. the other is about the practical physical losses in the system.

* Of course what is gained as 'advantage' in force is counterabalanced by an increase of 'distance moved'.

I'm sure others will add a more rigorous alaysis...and I'm will ing to be shot down on the detail. But this is probably a good start point.

Del

Many years ago, when I was at school, the simplest way of finding the efficiency of a mechanical system was taught as:

Efficiency = MA/VR

Where MA is mechanical advantage (load / applied force)

and VR is velocity ratio (distance moved by applied force / distance moved by load)

and I'm will ing to be shot down on the detail. But this is probably a good start point.

Del>

Nobody dares to shoot a simple truth-and all the truth -down!

good start point-- You can say THAT again.

Mechanical advantage deals with how much force one has to put in to move a given load

MA = load/ Force(used to lift the load)

Efficiency has to do with the ratio of the work done on the load to the energy used up in moving the load

E = work done on load / energy used up to move load (usually expressed as a percentage - 100% or less max E = 100%)

A pulley system or a lever (a long pole -stick pipe) can increase mechanical advantage - that is, you can use it to move something heavier than you can normally lift by your self

MA is usually a number greater than one (1) so a MA of 4 means you only require a quarter of the weight of a load (a bag of potatoes on a pulley) to lift it.

For a lever the efficiency =

E = (weight of load X distance moved)/force that 'you' apply X the distance moved

In an ideal system the energy you put in should be the energy you get back out but this is never possible so that efficiency is never 1 or 100%

hope that helps

thanks a lot for all....