Q.A force is applied to a 5 kg medicine ball, producing an acceleration of 4 m/s^2. Using F = ma, the force applied is:

Newton’s Laws of Motion

You already know motion from the inside. When a bus lurches forward, you are thrown backward. When it stops suddenly, you lurch forward. That feeling in your body — the pull, the push, the resistance — is exactly what Newton’s three laws describe. They are not abstract rules written in a book. They are the logic of how every moving thing behaves, from a cricket ball to a planet.

First Law: The Law of Inertia

A book lying on a table stays there forever unless someone picks it up. A ball rolling on a flat ground keeps rolling unless friction or a foot stops it. This is the first law: an object at rest stays at rest, and an object in motion stays in motion at the same speed and in the same straight line, unless an outside force acts on it.

The key idea is inertia — the natural unwillingness of any object to change its state of motion. Heavier objects have more inertia. A truck is harder to push than a bicycle, and once moving, harder to stop. Inertia is not laziness; it is a fundamental property of mass. …