Track quiz
Here are the eight rules first. Use them if a question feels hard.
| Idea | The rule |
|---|---|
| Where it is | Position is distance and direction from a reference point. Right of the point is positive. Left is negative. |
| Distance and displacement | Distance is the whole length of the path. Displacement is the change in position, with a direction. |
| Speed and velocity | Average speed is total distance divided by time. Average velocity is displacement divided by time. |
| Acceleration | Acceleration is the change in velocity divided by the time taken. Its unit is metre per second squared. |
| Steady and changing motion | Uniform motion covers equal distances in equal times, however short. Otherwise the motion is non-uniform. |
| Reading a graph | On a position-time graph, the slope is the velocity. On a velocity-time graph, the slope is the acceleration. These shapes are for motion in one direction. |
| Area under the line | The area under a velocity-time line is the displacement. For constant acceleration, v = u + at and s = ut + ½at². |
| Round and round | In uniform circular motion, the speed is constant. The direction of the velocity keeps changing. So the motion is accelerated. |
P is 30 m right of S. Q is 90 m right of S. What is P's position if Q is the reference point?
A cyclist rides 90 m right, then 20 m back. What are the distance and displacement?
A bus goes 150 m out and 150 m back. It takes 30 s. What is its average velocity?
A cart goes from 4 m/s to 13 m/s in 6 s. What is its acceleration?
In successive seconds an object covers 2, 4, 6 and 8 m. What kind of motion is it?
A velocity-time graph is a straight line that falls to zero. What is happening?
A car starts at rest. It speeds up steadily to 12 m/s in 4 s. How far does it go in those 4 s?
A stone whirls in a circle at a steady 5 m/s. Is its acceleration zero?
A car moves 60 m to the right in 5 s. What is its average velocity?
A bus moves to the right and slows down. Which sign fits its acceleration?
This is Chapter 4 of your Class 9 book, Exploration. It is called Describing Motion Around Us. Read it this week.
Next is Exploring Mixtures and their Separation. It changes the question again. Now you ask what a thing is made of.