A screw is a simple machine where an inclined plane is wrapped around a cylinder. The mechanical advantage created by a screw is based on the closeness of the threads of a screw. A mechanical advantage is when an input force is amplified by the use of a tool.
In order to calculate the mechanical advantage of a screw, take the length of the threads divided by the length of the screw.
Ideal Mechanical Advantage = Length of Threads / Length of Screw
Example:
If the length of the threads of a screw are 6cm long and the length of a screw is 3cm long, what is the mechanical advantage of the screw?
Length of Threads = 6cm
Length of Screw = 3cm
Ideal Mechanical Advantage = Length of Threads / Length of Screw
Ideal Mechanical Advantage = 6cm / 3cm
Ideal Mechanical Advantage = 2
The screw in our example is able to amplify the input force by two times.
