How to Calculate Velocity Ratio
In linear displacement, velocity ratio refers to the ratio of movement of load to the movement of effort. It also refers to gear ratio in rotational motion. Gear ratio is the ratio between the number of teeth in the pedal gear to the number of teeth on the sprocket.
In an ideal machine, the product of the velocity ratio with advantage is one. Advantage is the ratio between load and effort. In any machine, as the velocity ratio increases, the speed of the machine deceases.
Read the question twice and note down information given in the question. Depending on the question the information could be the number of teeth on the pedal gear and the sprocket, distance moved by driven and driver pulley, rotations per minute (rpm) of driven and driver pulley or the diameter of the driven and driver pulley.
Divide the number of teeth on the pedal gear by the number of teeth on the sprocket. When the number of teeth on the sprocket is higher than the number of teeth on the pedal gear, it is easier to cycle up steep hills, but the speed will decrease.
Determine whether the driver pulley or driven pulley has to be first. This information will be given in the question. The driver pulley is the pulley attached to the motor or the pedal of a bicycle.
Divide the rpm of the first pulley by the rpm of the second pulley.
Divide the distance moved by the first pulley by the distance moved by the second pulley. Alternatively, this can be expressed as the diameter of the first pulley by the diameter of the second pulley.