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!

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