# Mention some practical applications which mak use of the property of momemt of inertia.

Dear Student,

First let me give you an intuitive explanation on MOMENT OF INERTIA (will be referring to as MOI)

consider a solid disc of radius 'R' of certain mass rotating about its own axis passing through the center

Now consider a solid sphere of same mass rotating at a distance same as radius 'R' of the disc.

(Both the cases have a moderate speed.)

If you try stopping these two rotating bodies,you will be able to stop the solid disc easily compared to that of the solid sphere. Stopping the solid sphere requires a significant effort.

Inference-MOI of the latter case is very high compared to the first case.

MOI is used to measure or quantify the mass situated at the extremities of an object.

Few applications of MOI-

• FLYWHEEL of an automobile.     Flywheel is a heavy mass mounted on the crankshaft of an engine. The magnitude of MOI of the flywheel is very high and helps in storing the energy.
• Hollow shaft- An hollow shaft transmits more power compared to that of a solid shaft(both of same mass). The MOI of hollow shaft is more compared to that of a solid shaft. ( In a way, the mass at the center of solid shaft is removed and is stacked at the periphery and hence increasing its moment of inertia).
• Shipbuilding- MOI has a big impact on shipbuilding. A ship may sink by rolling but a ship will never sink by pitching. The reason is, the MOI over pitching axis is significantly huge compared to that over rolling axis.

In battleships the MOI inertia is high in order to reduce the time period of oscillation as a result of any disturbance.

In the above application the MOI is increased by just placing the significant amount mass away from the axis of rotation or oscillation.