Simple Machine: Screw
By: Elyssa DiRienzo
What is a screw?
A screw is a combination of two objects: inclined plane and a cylinder or base. Screws use friction to hold object together and can also be used to crush things or bore holes.
Mechanical advantage
The mechanical advantage of a screw can be found by dividing the circumference of the screw by the length of the screw.
MA= 3.14d/l
So if the diameter of a screw is 7mm and the length of the screw is 10mm, you would multiply the diameter by pi to get the circumference, then divide by the length (10) 21.98/10= 2.198. MA= 2.198
Some more examples
Barrel rifling
In firearms, the barrel has helical grooves that spin the projectile to give more accuracy, like the spin of a football.
Jar lid
Jar lids have a threaded lid so friction would prevent the lid from falling off
Corkscrew
The corkscrew uses a spiraled inclined plane to decrease the amount of force necessary to drill holes.