Applications of inertia

All objects resist a change in their state of motion. The tendency of undisturbed objects to stay at rest or to keep moving with the same velocity is called inertia. This is why, the first law of motion is also known as the law of inertia. We tend to remain at rest with respect to the seat until the drives applies a braking force to stop the motorcar. With the application of brakes, the car slows down but our body tends to continue in the same state of motion because of its inertia. A sudden application of brakes may thus cause injury. Safety belts are worn to prevent such accidents as they exert a force on our body to make the forward motion slower. When we are standing in a bus and the bus begins to move suddenly we tend to fall backwards because the sudden start of the bus brings motion to the bus as well as to our feet in contact with the floor of the bus. But the rest of our body opposes this motion because of its inertia.

When a motorcar makes a sharp turn at a high speed, we tend to get thrown to one side due to the law of inertia. We tend to continue in our straight-line motion.