Class 9 Science Chapter 4, Describing Motion Around Us, is the kinematics chapter. It studies motion in its idealised forms, first in a straight line and then uniform circular motion, and teaches you to describe it with numbers, graphs and the equations of motion.
What Class 9 Science Chapter 4 Covers
4.1 Motion in a Straight Line defines position from a reference point, distance travelled and displacement, average speed and average velocity, and average acceleration.
4.2 Graphical Representation of Motion teaches plotting, then reading position-time and velocity-time graphs.
4.3 Kinematic Equations derives the equations for motion in a straight line with constant acceleration.
4.4 Motion in a Plane introduces uniform circular motion, where the speed is constant but the direction keeps changing.
Exercises in Chapter 4
- Revise, Reflect, Refine numericals on displacement, velocity, acceleration and graphs, including a question about a speed-limit sign.
- The Journey Beyond suggests measuring acceleration with a smartphone’s accelerometer, a spinning cardboard disc, and talking to a mechanic about braking distance.
Read Class 9 Science Chapter 4 Online
More Chapters
- Previous: Chapter 3: Tissues in Action
- Next: Chapter 5: Exploring Mixtures and their Separation
- Hindi medium: Class 9 Science Chapter 4 PDF in Hindi (Anveshan)
- All Science chapters and the other Class 9 books: Class 9 NCERT books 2026-27
FAQ
What is the difference between distance and displacement?
Distance is the total length of the path travelled. Displacement is the net change in position from start to end, with direction.
Which equations of motion are in Class 9 Science Chapter 4?
The kinematic equations for motion in a straight line with constant acceleration, derived in section 4.3.