When the bus starts suddenly, the body momentarily leans backward. On the other hand, when the bus stops, the body is leaned forward. This is due to the nature of the object to maintain its current state of motion when no force is applied to it. This property of an object is called 'inertia.'

Our life and inertia

If you are shaking the seasoning bottle, the seasoning will come out through the hole because seasoning tries to keep moving.
When riding a car, you must fasten your seat belt. This is to prevent accidents in which a person flies forward due to inertia when a running car suddenly stops.
Besides, a seismometer that records earthquakes is an example of using inertia. When an earthquake occurs, the seismometer shakes with the ground. However, the heavyweight on the seismograph does not shake because of its inertia and is still in place, allowing you to record an earthquake.

The amount of inertia

The amount of inertia depends on the mass of the object. When running cars and trains press the brakes, the car stops easily, but the train does not stop easily. This is because the larger the mass of the object, the larger the inertia.