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Motion in a Straight Line – Class 11 Physics NCERT | Equations, Derivations & Graphs

📘 Motion in a Straight Line – Class 11 Physics (NCERT)

This topic explains motion along a straight line (also called one-dimensional motion) as per Class 11 NCERT Physics syllabus. It covers the essential concepts, formulas, and derivations required for CBSE and NEET preparation.

🔍 Key Concepts

  • Displacement (s): Change in position with direction
  • Velocity (v): Speed with direction (vector)
  • Speed: Distance traveled per unit time (scalar)
  • Acceleration (a): Rate of change of velocity
  • Time (t): Total duration of motion

🧾 Equations of Motion (Under Constant Acceleration)

The following three equations apply when acceleration is uniform:

1️⃣ First Equation

v = u + at

2️⃣ Second Equation

s = ut + ½at²

3️⃣ Third Equation

v² = u² + 2as

📐 Derivations

From definitions:

  • Acceleration: a = (v - u)/t → v = u + at
  • Displacement using average velocity:
    Average velocity = (u + v)/2
    s = [(u + v)/2] × t → s = ut + ½at²
  • Eliminating time: From above, derive v² = u² + 2as

📊 Motion Type Table

Type Acceleration Equations
Uniform Motion 0 s = vt
Freely Falling g s = ut + ½gt², v = u + gt
Thrown Upward -g s = ut - ½gt², v = u - gt

📋 Formula Summary Table

Quantity Symbol SI Unit Formula
Displacement s meter (m) s = ut + ½at²
Velocity v m/s v = u + at
Acceleration a m/s² a = (v - u)/t
Time t second (s) t = (v - u)/a

📈 Graphs Coming Soon!

We’ll soon add velocity-time and displacement-time graphs for visual understanding. Stay tuned!

Tags: Class 11 Physics, Kinematics, Equations of Motion, CBSE, NCERT Physics, Science Blog, One Dimensional Motion

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