Motion
Distance, displacement, velocity, acceleration, and equations of motion.
Chapter Overview
Uniform motion: equal distances in equal time intervals. Non-uniform: velocity changes.
Motion describes change in position with time. You study distance vs displacement, speed vs velocity, acceleration, equations of uniformly accelerated motion, and graphical interpretation of motion.
Basic Quantities
Speed
speed = distance / time
Velocity
velocity = displacement / time (vector)
Acceleration
a = (v − u) / t
Average speed
total distance / total time
Equations of Motion (u.a.m.)
First
v = u + at
Second
s = ut + ½at²
Third
v² = u² + 2as
Graphs
- Distance-time: slope = speed
- Velocity-time: slope = acceleration; area = displacement
- Uniform acceleration → straight line on v-t graph
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Equation of motion
Car starts from rest, a=2 m/s². Find v after 5 s and distance.
- 1u=0, v=u+at=10 m/s
- 2s=ut+½at²=0+½(2)(25)=25 m
Answer
v=10 m/s, s=25 m
Average speed
60 km in 1 h, then 40 km in 2 h. Average speed?
- 1Total distance=100 km
- 2Total time=3 h
- 3Avg speed=100/3≈33.3 km/h
Answer
≈ 33.3 km/h
Key Points to Remember
- ✓ Displacement is shortest vector distance
- ✓ SI unit of acceleration: m/s²
- ✓ Negative acceleration = retardation
Exam Tips
- • Choose correct equation — list u, v, a, s, t
- • Convert km/h to m/s: multiply by 5/18
- • Interpret graph slopes and areas
Practice MCQs — Motion
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
SI unit of velocity is: