How can a gear ratio be calculated?

A gear ratio is an essential concept in mechanics, particularly in systems involving gears. It is calculated by comparing the number of teeth on two interacting gears. Specifically, the gear ratio is determined by the formula:

Gear Ratio = Number of Teeth on Gear A / Number of Teeth on Gear B

This comparison indicates how many turns one gear must make to complete a turn of another gear. For instance, if the first gear has 10 teeth and the second gear has 20 teeth, the gear ratio would be 1:2, meaning the first gear must turn twice to make the second gear turn once.

The other options involve factors that do not accurately represent the calculation of gear ratios. The distance between the center of the gear to the point of contact deals with the physical dimensions and spacing of the gears, not the relationship between their rotations. Surface area comparisons would not influence gear performance or rotations in the context of gear ratios. Finally, while the speed of rotation can be linked to the gear ratio, the calculation itself is fundamentally based on the number of teeth on the gears rather than the speed of rotation directly. Therefore, understanding the relationship through the number of teeth is the most accurate way to calculate and define a gear ratio.