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.
πΉ 1. Types of Motion
Translatory motion: Whole body moves from one place to another (e.g. car).
Rotatory motion: The Body rotates around an axis (e.g. fan blades).
Oscillatory motion: Back and forth motion about a mean position (e.g. pendulum).
Rectilinear motion: Along a straight line.
Curvilinear motion: Along a curved path.
πΉ 2. Scalar vs Vector in Motion
Distance: Scalar
Displacement: Vector
Speed: Scalar
Velocity: Vector
Acceleration: Vector
πΉ 3. Uniform and Non-uniform Motion
Uniform Motion: Equal distances in equal time intervals.
Non-uniform Motion: Unequal distances in equal intervals (acceleration or deceleration involved).
πΉ 4. Graphical Representation
Distance-Time Graph:
Slope = Speed
Straight line β Uniform speed
Curve β Non-uniform speed
Velocity-Time Graph:
Slope = Acceleration
Area under the graph = Displacement
πΉ 5. Equation Of Uniformly Accelerated Motion
v = u + at
s = ut + Β½atΒ²
vΒ² = uΒ² + 2as
Where:
u = initial velocity
v = final velocity
a = acceleration
t = time
s = displacement
πΉ 6. Acceleration & Retardation
Acceleration: Increase in velocity (positive).
Retardation: Decrease in velocity (negative acceleration).
πΉ 7. Free Fall and Gravity
Object falling under gravity:
Acceleration = g = 9.8 m/sΒ² (downward)
Use motion equations with a = g
πΉ 8. Important Units
Speed/Velocity: m/s
Acceleration: m/sΒ²
Distance/Displacement: m
Time: s
π§ Quick MCQ Tips
Displacement can be zero even if the distance is not.
Uniform speed means zero acceleration.
A body can have a constant speed but changing velocity (e.g., circular motion).
Area under the v-t graph = displacement.
If acceleration is zero, motion is uniform.