Newton’s First Law, known as the “Law of Inertia,” states that every object tends to maintain its current state. That is, if an object is at rest, it remains at rest, and if it is in motion, it continues moving at the same speed and in the same direction unless an external force acts upon it.
Inertia is essentially an object’s resistance to changes in its state of motion. The greater the mass of an object, the greater its inertia, and the harder it is to change its motion. This is why stopping a truck is much more difficult than stopping a bicycle.
A common everyday example of this law can be seen during sudden braking in a car. When the car suddenly stops, passengers’ bodies tend to continue moving forward. Seat belts are designed precisely to counteract this effect.