Design and Technology
My Own Personal Yellow Brick Road
Mechanical Equations
Categories: Mechanisms

Now we’re getting into the details…

So, ready for more mathsy goodness? :)

There are three important formulas to remember when dealing with mechanisms…

Mechanical Advantage

This is basically a comparison of the effort put in to the load moved, this leverage is the ration of the distances of the effort and load to the fulcrum. When you work out this ration you can tell how the lever will work:

You work this out by using this equation:

For example the effort taken to lift a load in a wheel barrow:

Any number greater than one is a mechanical advantage and the higher the number the better the advantage.

Velocity Ratio

The velocity ratio is the distance moved by the effort divided by the distance moved by the load. An easy way to remember it is that it’s the opposite to mechanical advantage, so effort over load rather than load over effort.

Using the same example of the wheel barrow:


Last but not least efficiency is exactly what it says on the tin, how efficient is your mechanism?

You need the previous two worked out to get this as the equation is:

So our wheel barrow is…

196% efficient! This is because you can lift more than you normally would be able to by using a wheelbarrow.

Really useful stuff :)

Comments are closed.