Skip to main content

Laws of Motion – Class 11 Physics NCERT | Newton’s Three Laws, Formulas & Derivations

🧲 Laws of Motion – Class 11 Physics (NCERT)

The Laws of Motion were given by Sir Isaac Newton and are fundamental to understanding force, motion, and mechanics in physics. This chapter from Class 11 NCERT explains how forces affect the motion of objects.

📘 Newton's First Law of Motion (Law of Inertia)

Statement: A body remains at rest or in uniform motion in a straight line unless acted upon by an external force.

🔹 This law defines inertia – the natural tendency of objects to resist change in their motion.

Inertia depends on mass. More mass → more inertia.

📌 Real-Life Example: You fall forward when a bus suddenly stops.

📘 Newton's Second Law of Motion

Statement: The rate of change of momentum of an object is directly proportional to the applied force and takes place in the direction of the force.

✅ Derivation:

  • Momentum, p = mv
  • Rate of change of momentum = d(mv)/dt = m dv/dt = ma (if mass is constant)
F = ma

📌 This is the most useful equation for calculating force, acceleration, or mass.

Units:

  • Force: Newton (N)
  • 1 N = 1 kg·m/s²

📘 Newton's Third Law of Motion

Statement: For every action, there is an equal and opposite reaction.

Faction = – Freaction

📌 Examples:

  • A gun recoils when a bullet is fired.
  • We walk forward by pushing backward on the ground.

📚 Summary Table: Newton’s Laws of Motion

Law Meaning Formula
1st Law Inertia – object stays at rest or constant motion unless acted upon —
2nd Law Force = rate of change of momentum F = ma
3rd Law Every action has an equal and opposite reaction F1 = –F2

⚠️ Important Notes:

  • Friction opposes motion and acts opposite to applied force.
  • Contact forces include tension, normal force, friction.
  • Non-contact forces include gravitational, magnetic, electric forces.

📈 Applications of Newton's Laws

  • Free body diagrams
  • Calculating net force on bodies
  • Solving pulley problems and block motion

Tags: Laws of Motion, Newton’s Laws, Class 11 Physics, CBSE, NCERT, JEE NEET Physics, Science Blog

Labels:

Comments

Post a Comment

Thanks for your comments

Read this Article

Jharkhand D2D exam syllabus

  Jharkhand D2D lateral entry Syllabus * Mathematics * • Complex number • Numerical analysis • Application of derivatives • Statistics • Differentiation • Limits • Set relation and function • Inverse trigonometric function • Matrices and determinant • Continuity • Integration ( definite and indefinite) • Application of integration • Differential equation • Vector • Co ordinate geometry and 3D • Probability • L.P.P • Logarithm • Sequence and series • Trigonometry • Binomial theorem • Partial fraction ___________________ ___________________ * Chemistry * • Solid state • Solution • Chemical kinetics • Chemical bonding • Periodic table • Aldehyde/ ketone/ Carboxylic Acid • Co-ordination Compound • Surface chemistry • Hydrocarbon • Amines • Bio molecules • Polymer • Mole concept • Thermodynamics • D and F blocks • Halo alkane/ Halo arene • Basic concepts of organic chemistry • Environmental chemistry • P-block • Chemical equilibrium • Metallurgy • Ether/ alcohol/ phenol • Atomic s...
Post a Comment
Read more

All About the Sun: Formation, Age, Working Principle & Facts

All About the Sun: Formation, Age, Working Principle & Facts ☀️ Everything About the Sun The Sun is not just a glowing object in the sky. It’s a massive, powerful star that keeps our planet alive. In this article, we’ll explore how the Sun was formed, how it works, its structure, age, and future — in the simplest terms. 🌌 How the Sun Was Formed About 4.6 billion years ago, a huge cloud of gas and dust (a solar nebula) collapsed due to gravity. This led to the creation of a hot core — the protostar. As the core became hotter, nuclear fusion began, forming the Sun. Read More 🌫️ Nebula Collapse: Gravity pulled gas and dust inward. 🔥 Protostar Formed: A dense, hot core appeared. ☀️ Fusion Ignition: Hydrogen atoms fused into helium. 🌞 Main-Sequence Star: The Sun was born! ⏳ Age of the Sun The Sun is estimated to be 4.6 billion years old . It is in the middle of...
Post a Comment
Read more