Question

A small gear has a diameter of 7 cm.
A larger gear of diameter 21 cm is attached to it. How many rpm is the speed of larger gear if smaller one rotates at the speed of 180 rpm.

Answer 1

diameter of the small gear = 7 cm

diameter of large gear=21 cm

speed of small gear=180rpm

therefore,

speed of large gear=(180×21)/7

=540 rpm

hence the answer is 540 rpm