What does "gear ratio" refer to in mechanical systems?

Gear ratio is a critical concept in mechanical systems that relates to the interconnection of gears. It specifically refers to the ratio of the number of teeth on two meshing gears. When two gears are engaged, the gear ratio determines how many turns one gear must make in relation to the other.

For instance, if a driving gear with 10 teeth meshes with a driven gear with 20 teeth, the gear ratio would be 1:2. This means that for every complete revolution of the driving gear, the driven gear will make half a revolution.

The significance of the gear ratio lies in its direct impact on speed and torque in mechanical systems. A higher gear ratio generally means that for every single rotation of the input gear, the output gear will rotate more slowly but with increased torque. Conversely, a lower gear ratio leads to faster output, with reduced torque.

Understanding how gear ratios work is essential for applications such as automotive transmissions and machinery, where precise control over speed and torque is required. This makes the number of teeth on meshing gears crucial to the functionality of the system, clearly highlighting why this is the correct answer to the question posed.