CBSE Class 7 Science Important Questions Chapter 9 - Motion and Time

1. What is motion, and can you give an example?

Motion is the change in the position of an object over time. For example, a car moving along a road is in motion because its position relative to other objects changes as time passes. Motion can be in a straight line, circular, or even irregular.

2. How is speed defined, and what does it tell us about an object’s motion?
Speed describes how fast an object is moving by measuring the distance covered in a certain amount of time. It gives an idea of how quickly or slowly something is moving, like a car on a highway or a person walking. Higher speed means covering more distance in less time.

3. What is uniform motion, and can you give an example?
Uniform motion occurs when an object covers equal distances in equal intervals of time, regardless of how short or long these intervals are. An example is a train moving at a constant speed; it will cover the same distance every second or minute, showing uniform motion.

4. What is non-uniform motion, and how does it differ from uniform motion?
Non-uniform motion occurs when an object covers different distances in equal intervals of time. For instance, a cyclist speeding up and slowing down due to road conditions experiences non-uniform motion. This type of motion means the speed of the object is constantly changing.

5. Why is time measured, and what is its standard unit?
Time measures the duration of events or actions, letting us track when they begin, end, and how long they last. The standard unit of time is seconds, but other units like minutes and hours are commonly used as well, depending on the situation.

6. What is a speedometer, and how is it used?
A speedometer is an instrument found in vehicles to measure their current speed. It shows how fast the vehicle is going at any moment, helping drivers maintain safe speeds. The needle or digital display gives a reading that updates constantly as the vehicle’s speed changes.

7. How do distance and displacement differ from each other?
Distance is the total path covered by an object, while displacement is the shortest, straight-line distance between the starting and ending points. Distance doesn’t account for direction, but displacement does, showing how far and in what direction the object has moved.

8. A cyclist covers a distance of 60 km in 3 hours. What does this information tell us?
This information tells us how far the cyclist travelled and the time taken. From this, we can understand the rate at which the cyclist was moving. Knowing both distance and time helps us understand how steady or variable the cyclist’s pace was.

9. What is periodic motion, and what is a common example?
Periodic motion is a type of motion that repeats at regular intervals. An example is the swinging of a pendulum, which moves back and forth consistently. Other examples include the Earth’s orbit around the sun and the ticking of a clock.

10. How is speed different from velocity?
Speed measures how fast an object is moving, without considering direction, making it a scalar quantity. Velocity, on the other hand, includes direction, making it a vector quantity. For example, if a car moves 60 km/h north, we describe its velocity, not just its speed.

11. Why is velocity important when describing motion?
Velocity helps us understand both how fast an object is moving and in which direction. It provides more information than speed alone, which is important in cases like navigation or when two moving objects interact. Knowing velocity helps in predicting an object’s path.

12. What is oscillatory motion, and can you give an example?
Oscillatory motion is a type of repetitive motion around a central point or position. A common example is a pendulum that swings back and forth. This kind of motion is also found in springs and vibrating guitar strings, where they move to and fro around a fixed point.

13. If distance remains constant, how are speed and time-related?
When distance is constant, speed and timeshare an inverse relationship. This means if speed increases, the time taken to cover the same distance decreases. Similarly, if speed decreases, more time is needed to cover the same distance.

14. What does it mean when someone walks a distance of 500 meters in 10 minutes?
This statement means the person covered 500 meters of ground in 10 minutes. It provides an idea of how fast they were moving over a specific time, helping us understand their walking pace, whether it was brisk, slow, or steady.

15. What is acceleration, and why is it significant in motion?
Acceleration refers to how quickly an object’s velocity changes over time, either by speeding up, slowing down, or changing direction. It’s important to understand how forces affect motion, such as in vehicles that accelerate when they pick up speed on a road.

16. Explain rectilinear motion and give an example.
The rectilinear motion refers to movement in a straight line. For example, a train moving along a straight track is in rectilinear motion. This type of motion can be seen in daily life where objects move directly from one point to another without curving.

17. Why is the motion of a clock’s hands considered periodic?
The motion of a clock’s hands is considered periodic because they move at constant intervals. The second, minute, and hour hands move in a predictable, repeating way, making them good examples of periodic motion that keeps track of time.

18. If you know the speed and time, how can you find out how far something has moved?
By knowing speed and time, you can determine the total distance covered by an object. This is useful for understanding travel and movement, like figuring out how far a car has driven over several hours at a specific speed.

19. What does it mean if a train travels at 90 km/h for 4 hours?
This means the train maintained a steady rate of 90 kilometres per hour for 4 hours. This information tells us the train’s movement was uniform, allowing us to figure out the total distance it covered by the end of the journey.

20. Describe rotational motion and provide an example.
Rotational motion occurs when an object spins around a central point or axis. A good example is the Earth rotating on its axis, which leads to day and night. Other examples include wheels spinning on a car and fans rotating around their centre.

21. What is non-periodic motion? Give an example.
Non-periodic motion is a movement that doesn’t follow a regular, repeating pattern. An example is a car in traffic, where its motion stops, starts, and changes direction unpredictably. This type of motion varies and doesn’t repeat at fixed intervals.

22. How does knowing a car’s speed help in determining travel time over a fixed distance?
Knowing the speed of a car helps estimate the time needed to travel a certain distance. If the speed is steady, it’s easy to predict how long the journey will take, making planning easier, like estimating arrival times on road trips.

23. What instrument is used to measure time accurately, and why is it useful?
A stopwatch is used to measure time accurately, especially in experiments and sports. It records time precisely, sometimes to fractions of a second, helping in activities where exact timing is important, like races or scientific measurements.

24. What is average speed, and can you provide an example?
Average speed is the total distance covered divided by the total time taken. For instance, if a car drives 150 km in 3 hours with stops in between, the average speed gives a general idea of its pace over the entire journey.

25. What is a simple pendulum, and why is it often used in timekeeping?
A simple pendulum is a weight hanging from a fixed point that swings back and forth. It’s used in clocks because its regular, predictable motion makes it a reliable way to measure time, providing a steady rhythm that keeps time accurate.

5 Important Topics of Class 7 Science Chapter 9 You Shouldn’t Miss!

Benefits of Class 7 Chapter 9 Science Important Questions

• Clear Focus on Key Concepts - Important questions help students concentrate on essential topics like types of motion, speed, and time, making study sessions more focused.

• Improves Understanding of Graphs - These questions often involve distance-time graphs, helping students become familiar with interpreting and analysing graphical data.

• Better Exam Preparation - Practising important questions gives students an idea of the types of questions that may appear in exams, making them feel more prepared and confident.

• Strengthens Problem-Solving Skills - Working through these questions develops skills in calculating speed, distance, and time, reinforcing basic problem-solving abilities.

• Quick Revision Tool - Important questions summarise key points, allowing students to review the chapter’s main ideas efficiently before exams or tests.

Conclusion

CBSE Important Questions for Chapter 9, Motion and Time in Class 7 Science gives students a basic understanding of how objects move and how time, distance, and speed are measured. By exploring topics like types of motion, speed calculations, and distance-time graphs, students learn important principles of motion. This chapter also introduces practical skills for interpreting data and understanding the connection between distance and time, helping students gain a clear understanding of key science concepts.

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