Science Exploration Notes Class 9 English Medium 2026-27

Science Exploration Chapter 4. Describing Motion Around Us

CBSE Notes New Syllabus: Class 9

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Chapter 4. Describing Motion Around Us

This assignment is based on the complete chapter and follows the latest CBSE competency-based assessment pattern. It includes objective, descriptive, case-based and higher-order thinking questions to strengthen conceptual understanding and problem-solving skills.

Chapter Assignment

1. One Word Answer

1. The change in the position of an object with time.
2. A fixed point used to describe the position of an object.
3. The total length of the actual path travelled.
4. The shortest distance between the initial and final positions.
5. The distance travelled per unit time.
6. The displacement per unit time.
7. The rate of change of velocity.
8. Motion with constant speed.
9. Motion along a circular path with constant speed.
10. The SI unit of acceleration.

2. Fill in the Blanks

1. Motion is described with respect to a __________ point.
2. Distance is a __________ quantity.
3. Displacement is a __________ quantity.
4. Speed is measured in __________.
5. Velocity depends on __________.
6. Acceleration is the rate of change of __________.
7. In uniform motion, acceleration is __________.
8. The slope of a distance-time graph represents __________.
9. The area under a velocity-time graph gives __________.
10. Uniform circular motion has constant __________ but changing velocity.

3. True or False

1. An object can be at rest for one observer and in motion for another.
2. Distance can never be less than displacement.
3. Velocity is a scalar quantity.
4. Speed can never be negative.
5. Displacement may be zero even when distance is not zero.
6. Uniform motion means constant acceleration.
7. The slope of a velocity-time graph gives acceleration.
8. The area under a velocity-time graph gives displacement.
9. In uniform circular motion, the direction of motion changes continuously.
10. Acceleration is measured in m/s².

4. Match the Following

5. Very Short Answer Questions

1. Define motion.
2. What is a reference point?
3. Define distance.
4. Define displacement.
5. State the SI unit of speed.
6. Define average velocity.
7. What is acceleration?
8. What is uniform motion?
9. State one difference between speed and velocity.
10. Why is velocity a vector quantity?

6. Short Answer Questions

1. Differentiate between distance and displacement.
2. Differentiate between speed and velocity.
3. Explain the concept of a reference point with an example.
4. Describe uniform and non-uniform motion with examples.
5. Explain the importance of acceleration in daily life.
6. Differentiate between average speed and average velocity.
7. Explain why motion is relative.
8. Describe the characteristics of uniform circular motion.
9. Write any four applications of equations of motion.
10. Explain how graphs help in studying motion.

7. Long Answer Questions

1. Explain motion, reference point and position with suitable examples.
2. Describe distance and displacement with a comparison table.
3. Explain speed, velocity and acceleration along with their SI units and formulas.
4. Describe uniform and non-uniform motion with suitable examples.
5. Explain the graphical representation of motion.
6. Describe the position-time, distance-time and velocity-time graphs.
7. Explain the equations of motion and their applications.
8. Describe uniform circular motion and explain why it is an accelerated motion.
9. Explain the relationship between the slope and area of different motion graphs.
10. Discuss the importance of studying motion in science and everyday life.

8. Case Study Questions

Case Study – 1

A car travels 120 km in 2 hours on a straight highway at a constant speed.

1. What type of motion is shown by the car?
2. Calculate its average speed.
3. What will be the shape of its distance-time graph?
4. Is the acceleration zero or non-zero?

Case Study – 2

A student walks 20 m east and then 20 m west, returning to the starting point.

1. Calculate the total distance travelled.
2. What is the displacement?
3. Why are the values of distance and displacement different?
4. Which quantity is a vector?

Case Study – 3

A cyclist increases his speed from 5 m/s to 15 m/s in 5 seconds.

1. Has the cyclist accelerated or decelerated?
2. Calculate the acceleration.
3. Which graph can best represent this motion?
4. Which physical quantity changes during this motion?

Case Study – 4

A satellite revolves around the Earth with constant speed in a circular orbit.

1. What type of motion is shown by the satellite?
2. Why is the satellite considered to be accelerating?
3. Does its speed change?
4. What changes continuously during its motion?

Case Study – 5

A student observes a horizontal line on a distance-time graph.

1. What does the graph indicate?
2. What is the speed of the object?
3. Is the object moving or at rest?
4. How will the graph change if the object starts moving with uniform speed?

9. Competency-Based Questions

1. Why is a reference point necessary to describe motion?
2. How can two objects have the same speed but different velocities?
3. Why is displacement never greater than distance?
4. How does acceleration improve vehicle safety analysis?
5. Why is a velocity-time graph more informative than a distance-time graph?
6. How can graphs help compare the motion of two vehicles?
7. Why is motion in a circular path considered accelerated motion?
8. How are equations of motion useful in sports and transportation?
9. Why are SI units important while measuring motion?
10. How do graphical representations make the study of motion easier?

10. HOTS Questions

1. A person completes one full lap of a circular track. Explain why the distance is not zero but the displacement is zero.
2. Can an object have zero velocity and still have non-zero acceleration? Justify your answer.
3. Why is a person sitting inside a moving train considered both at rest and in motion at the same time?
4. A car moves with constant speed around a circular track. Why is its velocity not constant?
5. Can the average speed and average velocity of an object ever be equal? Explain with an example.
6. How would traffic management become difficult if the concepts of speed and acceleration were ignored?
7. Why is the slope of a graph considered more useful than only reading plotted points?
8. How do motion graphs help scientists predict future motion?
9. A vehicle returns to its starting point after a journey. Which quantities become zero and which remain non-zero? Explain.
10. Why is understanding motion considered the foundation for studying higher concepts of Physics?