Myths
Myth or fact?
Four claims often made about gears and machines. Choose myth or fact; the answers follow the sourced wording used on this site.
Energy is still conserved for these devices, because a machine cannot do more work than the energy put into it. OpenStax College Physics 2e
A machine can do more work than you put into it.
Gears must be circular.
The pinion always speeds things up.
Every gear must have at least five teeth.
If the teeth are arranged on noncircular bodies, the speed and torque ratios vary. Britannica Scholars: gear
If the pinion is on the driving shaft, the pair acts to reduce speed and to amplify torque. Britannica Scholars: gear
Because it is basically a screw, a worm gear may have only one thread (tooth). Britannica Scholars: gear