Motion in a Straight Line — Complete Lesson
Kinematics — Motion in One Dimension
Key Definitions
- Distance — total path length (scalar, always positive)
- Displacement — shortest distance from initial to final position (vector)
- Speed = distance / time (scalar)
- Velocity = displacement / time (vector)
- Acceleration = change in velocity / time (vector)
Equations of Motion (Uniform Acceleration)
v = u + at
s = ut + ½at²
v² = u² + 2as
where u = initial velocity, v = final velocity, a = acceleration, t = time, s = displacement
Graphical Analysis
| Graph | Slope gives | Area under curve gives |
|---|---|---|
| x-t graph | Velocity | — |
| v-t graph | Acceleration | Displacement |
Motion in a Straight Line — MCQ Practice
Motion in a Straight Line — Mnemonic
Mnemonic 1: For Equations of Motion (SUVAT) 🚗💨
"**S**peedy **U**rdu **V**ans **A**lways **T**ravel" 🚌
- S = Displacement (s)
- U = Initial velocity (u)
- V = Final velocity (v)
- A = Acceleration (a)
- T = Time (t)
Remember these letters to recall the 3 key equations of motion:
- v = u + at
- s = ut + ½at²
- v² = u² + 2as
Mnemonic 2: Hindi Phrase for Velocity and Acceleration Direction 🚦
"**गाड़ी की रफ्तार और दिशा से समझो त्वरित चाल**" (Gaadi ki raftaar aur disha se samjho tvarit chaal)
- गाड़ी की रफ्तार (Velocity) tells direction of motion.
- त्वरित चाल (Acceleration) can be in same or opposite direction.
This helps remember that velocity is a vector (magnitude + direction) and acceleration can speed up or slow down the object.
Mnemonic 3: For Types of Motion in Straight Line 🚶♂️🏃♀️
"**S-A-U**: Straight, Accelerated, Uniform" - SAU sounds like 'साऊ' (like 'sow')
- S - Straight line motion
- A - Accelerated motion (changing velocity)
- U - Uniform motion (constant velocity)
Think of a farmer (sow) walking straight, either steadily or speeding up!
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