Mechanical advantage (MA) is the factor by which a machine multiplies the force put into it.
Mechanical advantage is always calculated by the formula
- Load / effort.
The mechanical advantage can be calculated for the following simple machines by using the following formulas:
- Lever: MA = length of effort arm / length of resistance arm.
- Wheel and axle: A wheel is essentially a lever with one arm the distance between the axle and the outer point of the wheel, and the other the radius of the axle. Typically this is a fairly large difference, leading to a proportionately large mechanical advantage. This allows even simple wheels with wooden axles running in wooden blocks to still turn freely, because their friction is overwhelmed by the rotational force of the wheel multiplied by the mechanical advantage.
- Pulley: Pulleys change the direction of a tension force on a flexible material, e.g. a rope or cable. In addition, pulleys can be “added together” to create mechanical advantage, by having the flexible material looped over several pulleys in turn. More loops and pulleys increases the mechanical advantage.
Mechanical advantage – a measure of the force amplification achieved by using a tool, mechanical device or machine system.
- mechanical device
- mechanical system
In the case of ideal machine , when there is no friction mechanical advantage equals velocity ratio.
If velocity ratio and efficiency are known then MA = efficiency x velocity ratio.
Examples of mechanical advantage
- SUV opener – leverage and angles, where to put it to make a small movement to open the door.
- velocity – quickness of motion; speed; rate of occurrence or action; rapidity
- advantage, effort, force, efficiency, friction, velocity