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

Mercury Planet: Facts, Structure, Temperature and Complete Guide Mercury Planet: Complete Guide to the Smallest Planet Quick Navigation Introduction Basic Facts Structure of Mercury Surface Features Temperature Atmosphere Orbit and Rotation Water Ice Exploration Interesting Facts Conclusion Introduction Mercury is the smallest planet in the solar system and the closest planet to the Sun. Even though it is near Earth, it is difficult to observe because it stays very close to the Sun in the sky. Mercury is a rocky planet with many craters, similar to the Moon. Due to its proximity to the Sun, it experiences extremely hot days and very cold nights. Basic Facts About Mercury Distance from Sun: 57.9 million km Diameter: 4,880 km Year length: 88 Earth days Day length: 59 Earth days Moons: None Gravity: 38% of Earth Structure of Mercury Core Mercury has a massive iron core that makes up about 85%...
Post a Comment
Read more

शहीद भगत सिंह, sahid bhagat singh know about freedom fighters Static GK

  शहीद भगत सिंह 🇮🇳🇮🇳 ▪️भगत सिंह का जन्म 28 सितंबर, 1907 को बंगा गाँव, जिला - लायलपुर, पंजाब (वर्तमान पाकिस्तान) में हुआ था। ▪️इनका पालन-पोषण पंजाब के जालंधर ज़िले में संधू जाट किसान परिवार में हुआ। ▪️वर्ष 1923 में भगत सिंह ने नेशनल कॉलेज, लाहौर में प्रवेश लिया, जिसकी स्थापना और प्रबंधन लाला लाजपत राय एवं भाई परमानंद द्वारा किया था। ▪️वर्ष 1924 में भगतसिंह कानपुर में शचिन्द्र नाथ सान्याल द्वारा एक साल पहले शुरू किए गए हिंदुस्तान रिपब्लिकन एसोसिएशन (Hindustan Republican Association) के सदस्य बने तथा एसोसिएशन के मुख्य आयोजक चंद्रशेखर आज़ाद थे।  ▪️हिंदुस्तान रिपब्लिकन एसोसिएशन के सदस्य के रूप में भगत सिंह ने ‘बम का दर्शन’ (Philosophy of the Bomb) को गंभीरता से लेना शुरू किया। ▪️उन्होंने ब्रिटिश साम्राज्यवाद के खिलाफ सशस्त्र क्रांति को एकमात्र हथियार माना। ▪️वर्ष 1925 में भगत सिंह लाहौर लौट आए और अगले एक वर्ष के भीतर उन्होंने अपने सहयोगियों के साथ मिलकर ‘नौजवान भारत सभा’ नामक एक उग्रवादी युवा संगठन का गठन किया। ▪️अप्रैल, 1926 में भगत सिंह ने सोहन सिंह जोश के साथ संपर्क स्थापित...
Post a Comment
Read more

Tally Prime Keyboard Shortcuts – Boost Speed in Accounting (2025)

📊 Tally Prime Keyboard Shortcuts – Speed Up Your Accounting Tally Prime is one of the most widely used accounting software in India and beyond. Whether you're an accountant, business owner, or student, learning Tally shortcuts will save time and increase your efficiency. 💼 Master Shortcuts for Daily Use Shortcut Function Alt + F1 Detailed Report / Close Company Alt + F2 Change Period (Date range) Alt + F3 Company Info (Create/Alter/Select company) F1 Select Company / Help F2 Change Date F3 Switch Company 🧾 Voucher Entry Shortcuts Shortcut Voucher Type F4 Contra Voucher F5 Payment Voucher F6 Receipt Voucher F7 Journal Voucher F8 Sales Voucher F9 Purchase Voucher F10 Reversing Journal / Memo 📋 Inventory & Reports Shortcut Function Alt + G Go To (Open any report quickly) Ctrl + Enter Alter master while viewing report Alt + F12 Filter report (Advanced filtering) Ctrl + H Change m...
Post a Comment
Read more