Motion: Summary Note for MCQ
Motion is the change in position of an object with respect to time and surroundings. It is one of the most fundamental concepts in physics, forming the basis for understanding how and why things move.
🔹 1. Types of Motion
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Translatory motion: Whole body moves from one place to another (e.g. car).
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Rotatory motion: The Body rotates around an axis (e.g. fan blades).
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Oscillatory motion: Back and forth motion about a mean position (e.g. pendulum).
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Rectilinear motion: Along a straight line.
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Curvilinear motion: Along a curved path.
🔹 2. Scalar vs Vector in Motion
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Distance: Scalar
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Displacement: Vector
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Speed: Scalar
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Velocity: Vector
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Acceleration: Vector
🔹 3. Uniform and Non-uniform Motion
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Uniform Motion: Equal distances in equal time intervals.
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Non-uniform Motion: Unequal distances in equal intervals (acceleration or deceleration involved).
🔹 4. Graphical Representation
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Distance-Time Graph:
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Slope = Speed
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Straight line → Uniform speed
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Curve → Non-uniform speed
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Velocity-Time Graph:
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Slope = Acceleration
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Area under the graph = Displacement
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🔹 5. Equation Of Uniformly Accelerated Motion
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v = u + at
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s = ut + ½at²
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v² = u² + 2as
Where:
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u = initial velocity
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v = final velocity
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a = acceleration
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t = time
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s = displacement
🔹 6. Acceleration & Retardation
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Acceleration: Increase in velocity (positive).
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Retardation: Decrease in velocity (negative acceleration).
🔹 7. Free Fall and Gravity
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Object falling under gravity:
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Acceleration = g = 9.8 m/s² (downward)
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Use motion equations with a = g
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🔹 8. Important Units
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Speed/Velocity: m/s
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Acceleration: m/s²
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Distance/Displacement: m
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Time: s
🧠 Quick MCQ Tips
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Displacement can be zero even if the distance is not.
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Uniform speed means zero acceleration.
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A body can have a constant speed but changing velocity (e.g., circular motion).
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Area under the v-t graph = displacement.
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If acceleration is zero, motion is uniform.