Eli5, how does gears work?

Question

For example, I understand gears work with ratio (different sizes) that changes the speed of a car, but how exactly – & why does it do that?

Also, how does it connect with gears + revolutions per min (RPM)?

Thanks!

In: Engineering

Answer 1

As to the *why* they do that, gears are bunches of levers. Each tooth it a lever that starts at the center of the gear and ends at the tip of the tooth.

http://www.dynamicscience.com.au/tester/solutions1/hydraulicus/gears1mechanicalad.htm#:~:text=When%20two%20gears%20are%20meshed,the%20shaft%20of%20the%20follower.