Mechanical advantage:

In the design of a machine such as a gear, friction drives, levers, timing belts and screw drives, there has to be a transmission element between the energy source and the output motion.  This transmission system generally includes a gear ratio or a mechanical advantage. The mechanical advantage can increase either the output speed or the output torque. If you take the example of a gear on a bicycle, the low gear can be used to pedal easily up hill but it gives a lower speed to the bicycle. On the contrary, a high gear provides a higher speed to the bicycle but it requires more torque to turn the crank arm of the pedal. This is due to the law of conservation of energy and is the main concept of mechanical advantage. With a power source, you can get either a high velocity or a high torque but not both.

Mechanical advantage is an increase in the torque or the force that is achieved by a mechanism through a power transmission element. For devices that have rotational motion, the term gear ratio is used in place of mechanical advantage. Mechanical advantage is used to describe the components that exhibit translational motion.

As per the law of conservation of energy, one can never get more energy in the output motion than is provided by the source of energy. Instead, there is always some loss of energy in the transmission of power. During the basic analysis of gear ratios, frictional losses are neglected and their effect is incorporated separately. Therefore, the power input (change in energy divided by time) is equal to the power output by the power transmission system.

Questions:

• What does the law of conservation of energy state?
• What is mechanical advantage? How does it differ from gear ratio?