Objects tend to remain at rest due to inertia, an inherent property of matter. When the motorcar stops suddenly, the passengers inside experience a change in velocity, causing their bodies to resist this change. This resistance is described by Newton’s first law of motion. Until the brakes are applied, the car and its occupants share the same forward velocity. When the brakes decelerate the car, the passengers’ inertia keeps them moving at the original speed. It’s only when the brakes apply a force opposite to the car’s motion that the passengers feel pushed forward, causing them to move relative to the car’s interior.