Question

When does a machine act as (a) a force multiplier, (b) a speed multiplier? Can a machine act as a force multiplier and a speed multiplier simultaneously?

Answer 1

1. When the effort required to overcome a specific load is less than the load, the machine has a mechanical advantage greater than one (M.A. > 1) and functions as a force multiplier. In a machine, if the displacement of load is smaller than the displacement of effort and the velocity ratio is greater than one (V.R. > 1), it functions as a force multiplier. For example, pliers and a spoon are used to open the lid of a jar.
2. If a machine requires more effort than its load, it has a mechanical advantage of less than one (M.A. < 1) and acts as a speed multiplier. A machine with a velocity ratio of less than one (V.R. < 1) functions as a speed multiplier by displacing more weight than effort. For example, scissors are used to cut a piece of cloth with blades that are larger than the handles.
   A machine cannot function simultaneously as both a force multiplier and a speed multiplier. For a speed multiplier, M.A. and V.R. must be less than 1, while M.A. and V.R. must be greater for a force multiplier.