Physics · Chapter 02
🍎 Newton's Laws
Three laws that rule everything.
💡 Newton's Three Laws
1st Law (Inertia): An object at rest stays at rest; a moving object keeps moving — unless a force acts on it. That's why you jerk forward when a bus brakes suddenly.
2nd Law: Force depends on mass and acceleration:
F = m × a
Heavier objects need more force to accelerate. Push a bicycle and a truck with the same force — bicycle speeds up way more.
3rd Law: Every action has an equal and opposite reaction. A rocket pushes gas down, gas pushes rocket up. 🚀
Sir Isaac Newton — formulated 3 laws of motion (1687)Wikimedia Commons / Public Domain
Rocket launch — Newton's 3rd law: action-reaction propulsionWikimedia Commons / Public Domain
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Watch the Laws in Action
AnimationA force pushes the box. Bigger mass → smaller acceleration. Heavier box, harder to push.
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Test F = m × a
ExperimentChange the force or the mass. Watch the box accelerate faster — or struggle when heavier.
20 N
10 kg
Acceleration (F ÷ m)2.00 m/s²
A force of 20 N on 10 kg gives an acceleration of 2.00 m/s². Double the mass → half the acceleration.