Dynamics

Understanding forces, Newton's laws, and how forces cause motion

Topics

How does Newton's first law work?

Newton's first law states that an object at rest stays at rest, and an object in motion continues moving at constant velocity unless acted upon by an unbalanced force. This describes the property of inertia.

How does Newton's second law work?

Newton's second law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This is expressed as F = ma (force equals mass times acceleration).

How does Newton's third law work?

Newton's third law states that for every action, there is an equal and opposite reaction. When object A exerts a force on object B, object B simultaneously exerts an equal and opposite force on object A.

What is momentum?

Momentum is the quantity of motion an object has, calculated by multiplying its mass by its velocity. It describes how difficult it is to stop a moving object and is conserved in collisions.

Why do we have friction?

Friction exists because surfaces are not perfectly smooth—microscopic bumps and irregularities on surfaces interlock and resist motion. Friction helps us walk, grip objects, and control motion.