Class 9 Physics Chapter 1 Motion – All Formulas with Meanings and Units (CBSE Notes)

🚀 Class 9 Physics – Chapter 1: Motion – Important Formulas

This chapter is based on basic concepts of motion in physics. Here are all the formulas you need to learn, along with their meaning and SI units.

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📌 1. Speed

Speed = Distance / Time

Symbolically: v = d / t

• Speed (v) → m/s (meters per second)
• Distance (d) → meters (m)
• Time (t) → seconds (s)

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📌 2. Velocity

Velocity = Displacement / Time

Symbolically: v = s / t

• Velocity (v) → m/s
• Displacement (s) → meters

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📌 3. Average Speed

Average Velocity = Total Displacement /Total Time

Two important cases for calcualting average speed :

• If Total journey is divided into two equal parts with different speeds (v₁ and v₂) and distance are equal:

  Average Velocity = 2v₁v₂ / v₁+v₂

• If Total journey is divided into two equal time intervals with different speeds (v₁ and v₂):

  V_avg = (u + v ) / 2

• Average Velocity (v) → m/s (meters per second)
• Distance (d) → meters (m)
• Time (t) → seconds (s)

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📌 4. Average Velocity

Average Speed = Total Distance /Total Time

Also, if initial velocity (u) and Final Velocity (v) is given, Then

Average Velocity = (initial velocity + final velocity) / 2

Symbolically: V_avg = (u + v ) / 2

• Average Velocity (v) → m/s (meters per second)
• Distance (d) → meters (m)
• Time (t) → seconds (s)

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📌 5. Acceleration

Acceleration = Change in Velocity / Time

Symbolically: a = (v − u) / t

• a → acceleration in m/s²
• v → final velocity
• u → initial velocity
• t → time in seconds

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📌 6. First Equation of Motion

v = u + at

• v = final velocity
• u = initial velocity
• a = acceleration
• t = time

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📌 7. Second Equation of Motion

s = ut + ½at²

• s = displacement
• u = initial velocity
• a = acceleration
• t = time

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📌 8. Third Equation of Motion

v² = u² + 2as

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📘 Units Table (Quick Revision)

Quantity	Symbol	SI Unit
Speed	v	m/s
Velocity	v	m/s
Acceleration	a	m/s²
Time	t	seconds (s)
Distance/Displacement	d or s	meters (m)

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💡 Tip:

Remember: If acceleration is zero, then all three equations of motion collapse to v = u and s = ut.

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📥 Download PDF

[PDF link will be added soon]

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Stay tuned for Class 9 Chapter 1 Numericals and Concept Tricks in the next post!

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Labels: Class 9, Physics, Motion, Formulas