newton.

1st Law: Law of Inertia

💡 "An object at rest stays at rest, and an object in motion stays in motion with the same velocity unless acted upon by an external force."

Key Points:

  • If no net force acts on an object, its velocity remains constant (either at rest or in uniform motion).

  • Inertia is the tendency of an object to resist changes in its motion.

  • Mass (mm) is a measure of inertia → larger mass = more inertia.

🛑 Example:

  • A book on a table stays at rest until you push it.

  • A moving car continues moving until brakes (friction force) stop it.

2nd Law: Law of Acceleration

💡 "The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass."

Mathematical Formula:

F=ma

where:

  • F= net force (N)

  • m= mass (kg)

  • a = acceleration (m/s²)

Key Points:

  • A larger force produces greater acceleration.

  • A larger mass requires more force to achieve the same acceleration.

  • If no net force, then a=0a=0 (object moves at constant velocity or remains at rest).

3rd Law: Action-Reaction

💡 "For every action, there is an equal and opposite reaction."

Key Points:

Forces always come in pairs.

If object A exerts a force on object B, then B exerts an equal force back on A in the opposite direction.

⚖ Example:

A rocket launches by pushing gases downward, and the gases push the rocket upward.

When you push against a wall, the wall pushes back with equal force.