Question

Explain how a gear system can be used to obtain gain in speed? Given one example.

Answer 1

A gear system can be used to obtain gain in speed when the bigger wheel drives the smaller wheel, i.e. when the driving gear has more number of teeth than the driven gear.

To obtain gain in speed, the gear ratio should be more than one. Mathematically,
Gain in speed =`" 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑒𝑒𝑡ℎ 𝑖𝑛 𝑑𝑟𝑖𝑣𝑖𝑛𝑔 𝑤ℎ𝑒𝑒𝑙"/"𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑒𝑒𝑡ℎ 𝑖𝑛 𝑑𝑟𝑖𝑣𝑒𝑛 𝑤ℎ𝑒𝑒𝑙"`

Example: A toy motor car uses the gear principle to obtain gain in speed. It has a key and spring on the axle fitted with a driving gear having more teeth which engages the driven gear having fewer teeth. The wheels of the car are fitted on the axle of the driven gear.
When the key is turned clockwise (or the toy car is pulled back by hand) the spring is wound up. On releasing the key (or the toy car), the spring turns the driving gear anti-clockwise, which in turn rotates the wheels of the toy car clockwise and the car moves forward at a greater speed.