Important Questions Class 7 Science Chapter 8 Measurement of Time and Motion

Time helps us compare when events happen and how long they last.
Speed tells how much distance an object covers in a unit time.

Measurement of time and motion connects daily clocks, sports timing, pendulums, speed, distance, time and linear motion. Important Questions Class 7 Science Chapter 8 help students practise ancient time-measuring devices, simple pendulum, time period, SI unit of time, speed formula, distance-time relation, uniform linear motion and non-uniform linear motion. The CBSE 2026 chapter explains these ideas through Prerna’s sprint training, sundials, water clocks, pendulum clocks, railway timetable calculations and train motion examples.

Key Takeaways

• SI Unit of Time: The SI unit of time is second, written as s.
• Simple Pendulum: The time period of a simple pendulum of fixed length remains constant at a place.
• Speed Formula: Speed equals total distance covered divided by total time taken.
• Uniform Motion: An object in uniform linear motion covers equal distances in equal time intervals.

Important Questions Class 7 Science Chapter 8 Structure 2026

Important Questions Class 7 Science Chapter 8 with Answers

Measurement of Time and Motion explains how time intervals and motion are measured.
Students should write correct units and use formula steps in every numerical.
These measurement of time and motion class 7 questions follow the NCERT 2026 chapter flow.

1. What does Important Questions Class 7 Science Chapter 8 mainly teach?

Important Questions Class 7 Science Chapter 8 mainly teach time measurement, simple pendulum, SI unit of time, speed, average speed, uniform motion and non-uniform motion. The chapter connects clocks with motion calculations.

1. Time Skill: Identify time-measuring devices.
2. Pendulum Skill: Measure time period.
3. Speed Skill: Use speed = distance/time.
4. Motion Skill: Identify uniform and non-uniform motion.
5. Final Result: Chapter 8 teaches time measurement and speed-based motion.

2. What is the name of Class 7 Science Chapter 8?

The name of Class 7 Science Chapter 8 is Measurement of Time and Motion. It explains how time and motion are measured.

1. Chapter Number: 8.
2. Chapter Name: Measurement of Time and Motion.
3. Textbook: Curiosity.
4. Final Result: Chapter 8 is about time, speed and motion.

3. Why is accurate time measurement important in sports?

Accurate time measurement is important in sports because winners may finish almost together. Tiny time differences can decide race results.

1. Race Example: 100 metre sprint.
2. Need: Compare finishing times.
3. Modern Timing: Measures tiny fractions of a second.
4. Final Result: Accurate timing helps identify winners fairly.

Class 7 Science Chapter 8 Important Questions

Class 7 Science Chapter 8 important questions focus on measuring time and comparing motion.
The chapter uses watches, clocks, stopwatches, pendulums, trains and races as examples.
Students should solve motion questions using distance, time and speed.

4. Why did humans start measuring time?

Humans started measuring time because many natural events repeat after fixed intervals. They used these repeated events to track days and seasons.

1. Sunrise and Sunset: Mark a day.
2. Moon Phases: Repeat regularly.
3. Seasons: Change in a cycle.
4. Final Result: Repeated natural events helped early timekeeping.

5. What repeating natural events were used for timekeeping?

People used sunrise, sunset, phases of the Moon and changing seasons for timekeeping. These events occur in cycles.

1. Daily Cycle: Rising and setting of the Sun.
2. Monthly Cycle: Moon phases.
3. Yearly Cycle: Seasons.
4. Final Result: Natural cycles helped create calendars and time measures.

6. Why did people need smaller time-measuring devices?

People needed smaller time-measuring devices to measure intervals within a day. Calendars could not show the time of day.

1. Calendar: Measures days and months.
2. Daily Work: Needs shorter intervals.
3. Devices: Sundial, water clock, hourglass and candle clock.
4. Final Result: Smaller devices helped measure parts of a day.

7. Why do modern clocks use repeating processes?

Modern clocks use repeating processes because equal repetitions can mark equal time intervals. Quartz clocks and atomic clocks use rapid vibrations.

1. Basic Principle: Repetition.
2. Quartz Clock: Uses crystal vibrations.
3. Atomic Clock: Uses atomic vibrations.
4. Final Result: Clocks measure time using regular repeating processes.

Measurement of Time Class 7 Questions

Measurement of time class 7 questions explain ancient and modern ways of tracking time.
The chapter moves from natural cycles to clocks with high precision.
Time can be measured in seconds, minutes and hours.

8. What is measurement of time?

Measurement of time means finding the interval between two events or the duration of an event. Clocks and watches help measure time.

1. Event 1: Starting point.
2. Event 2: Ending point.
3. Time Interval: Difference between events.
4. Final Result: Time measurement tells how long an event lasts.

9. What instruments are used today to measure time?

Watches, wall clocks, stopwatches, mobile phones, Braille watches and talking watches measure time today. Different users need different devices.

1. Wall Clock: Shows time in a room.
2. Stopwatch: Measures race time.
3. Talking Watch: Announces time.
4. Final Result: Modern devices measure time in many ways.

10. What is a stopwatch?

A stopwatch is a special watch used to measure short time intervals. Sports teachers use it to time races.

1. Use: Measures race duration.
2. Control: Can start and stop quickly.
3. Example: School sprint timing.
4. Final Result: A stopwatch measures short time intervals.

11. Why are tiny fractions of a second important?

Tiny fractions of a second are important in sports, medicine, music and technology. They help measure events very accurately.

1. Sports: Decide close race results.
2. ECG: Measures heartbeat variations.
3. Computers: Process signals very fast.
4. Final Result: Small time intervals matter in modern life.

12. What is the smallest time interval shown by a common wall clock?

A common wall clock with a second hand can measure one second. One second is its smallest visible interval.

1. Clock Part: Second hand.
2. Smallest Interval: 1 s.
3. Use: Basic daily timekeeping.
4. Final Result: A wall clock can show one-second intervals.

Ancient Time Measuring Devices Class 7

Ancient time measuring devices class 7 questions cover sundials, water clocks, hourglasses and candle clocks.
These devices used shadows, flowing water, falling sand and burning candles.
Their accuracy was lower than modern clocks.

13. What were ancient devices used to measure time?

Ancient devices used to measure time included sundials, water clocks, hourglasses and candle clocks. They measured time through repeated or gradual changes.

1. Sundial: Uses shadow.
2. Water Clock: Uses flowing water.
3. Hourglass: Uses flowing sand.
4. Candle Clock: Uses burning candle marks.
5. Final Result: Ancient clocks used natural or steady changes.

14. How does a sundial measure time?

A sundial measures time using the changing position of a shadow. The Sun’s light casts the shadow on marked positions.

1. Source: Sunlight.
2. Object: Casts a shadow.
3. Change: Shadow position changes during the day.
4. Final Result: Sundials use shadows to show time.

15. Why can a sundial not work at night?

A sundial cannot work at night because it needs sunlight to cast a shadow. Without sunlight, no shadow position is available.

1. Required Source: Sun.
2. Night Condition: No sunlight.
3. Result: No useful shadow.
4. Final Result: A sundial works only in sunlight.

16. How does a water clock measure time?

A water clock measures time using the flow of water into or out of a vessel. Markings show the passage of time.

1. Water Flow: Happens gradually.
2. Markings: Indicate time intervals.
3. Type: Outflow or floating bowl.
4. Final Result: Water clocks use water movement to measure time.

17. How does a floating bowl water clock work?

A floating bowl water clock works when water enters a bowl through a small hole. The bowl fills in a fixed time and sinks.

1. Bowl: Has a small hole.
2. Water: Enters slowly.
3. Time Mark: Bowl sinks after fixed interval.
4. Final Result: The sinking bowl marks a time interval.

18. How does an hourglass measure time?

An hourglass measures time using sand flowing from one bulb to another. The amount of falling sand shows the time passed.

1. Material: Sand.
2. Path: Upper bulb to lower bulb.
3. Measurement: Flow duration.
4. Final Result: Hourglass measures time through falling sand.

19. How does a candle clock measure time?

A candle clock measures time through markings on a candle. As the candle burns, the level reaches different marks.

1. Candle: Has markings.
2. Burning: Happens gradually.
3. Time: Indicated by remaining candle level.
4. Final Result: Candle clocks use burning to show time.

20. What is Samrat Yantra?

Samrat Yantra is the world’s largest stone sundial at Jantar Mantar, Jaipur. It is about 27 metres high.

1. Location: Jaipur, Rajasthan.
2. Site: Jantar Mantar.
3. Function: Measures local solar time.
4. Final Result: Samrat Yantra is a large stone sundial.

Simple Pendulum Class 7 Questions

Simple pendulum class 7 questions explain periodic motion and time period.
A pendulum has a bob suspended from a rigid support by a long thread.
Its time period of fixed length remains nearly constant at a place.

21. What is a simple pendulum?

A simple pendulum consists of a small metallic ball called a bob suspended by a long thread from a rigid support. It can oscillate.

1. Bob: Small heavy ball.
2. Thread: Long and light.
3. Support: Rigid.
4. Final Result: A simple pendulum has a bob and thread.

22. What is the mean position of a pendulum?

The mean position is the rest position of the pendulum bob. It lies between the two extreme positions.

1. At Rest: Bob stays at mean position.
2. During Motion: Bob passes through mean position.
3. Label Example: O in the pendulum diagram.
4. Final Result: Mean position is the central rest position.

23. What are extreme positions in a pendulum?

Extreme positions are the farthest points reached by the bob on either side of the mean position. The bob changes direction there.

1. One Side: Extreme position A.
2. Other Side: Extreme position B.
3. Motion: Bob reverses at extremes.
4. Final Result: Extreme positions are turning points.

24. What is oscillatory motion of a pendulum?

Oscillatory motion is the to-and-fro motion of the pendulum bob about its mean position. It repeats after fixed intervals.

1. Motion: Back and forth.
2. Mean Position: Centre point.
3. Repetition: Same path repeats.
4. Final Result: Pendulum motion is oscillatory and periodic.

25. What is one oscillation of a simple pendulum?

One oscillation is completed when the bob returns to its starting position after passing through the other extreme. It may start from mean or extreme position.

1. From Mean: O to A to B to O.
2. From Extreme: A to B to A.
3. Completion: Starting position returns.
4. Final Result: One oscillation is one complete to-and-fro motion.

26. Why is pendulum motion periodic?

Pendulum motion is periodic because it repeats its path after a fixed interval of time. This interval is its time period.

1. Path: Repeats.
2. Time: Fixed interval.
3. Example: Same bob swings again and again.
4. Final Result: Pendulum motion repeats regularly.

Time Period of Pendulum Class 7

Time period of pendulum class 7 questions focus on measuring one complete oscillation.
The chapter measures time for 10 oscillations and divides it by 10.
Pendulum time period depends on length but not on bob mass.

27. What is time period of a pendulum?

Time period of a pendulum is the time taken to complete one oscillation. It is measured in seconds.

1. One Oscillation: Complete to-and-fro motion.
2. Quantity: Time taken.
3. Unit: Second.
4. Final Result: Time period is time for one oscillation.

28. How can the time period of a pendulum be measured accurately?

The time for 10 oscillations can be measured and divided by 10. This reduces small timing errors.

1. Step 1: Count 10 oscillations.
2. Step 2: Measure total time.
3. Step 3: Divide by 10.
4. Final Result: Time period = time for 10 oscillations/10.

29. Does time period of a pendulum stay the same every time?

Yes, the time period of a pendulum of given length is almost the same at a place. Small differences may occur due to measurement errors.

1. Same Length: Time period remains nearly constant.
2. Same Place: Same local conditions.
3. Observation: Readings are almost equal.
4. Final Result: A given pendulum has a nearly constant time period.

30. Does pendulum length affect time period?

Yes, pendulum length affects time period. Longer pendulums have a larger time period.

1. Short Pendulum: Smaller time period.
2. Long Pendulum: Larger time period.
3. Conclusion: Length matters.
4. Final Result: Time period increases with pendulum length.

31. Does bob mass affect time period of a pendulum?

No, bob mass does not affect the time period of a simple pendulum at a given place. Pendulums of the same length have the same time period.

1. Same Length: Time period same.
2. Different Bob Mass: No major change.
3. Condition: Same place.
4. Final Result: Pendulum time period does not depend on bob mass.

32. Why was the pendulum important in clocks?

The pendulum was important because its time period of fixed length is constant at a place. This helped mark equal time intervals.

1. Repeating Motion: Regular oscillation.
2. Fixed Time: Same period.
3. Clock Use: Timekeeping.
4. Final Result: Pendulum clocks used regular oscillations.

33. Who invented the pendulum clock?

Christiaan Huygens invented the pendulum clock in 1656 and patented it in 1657. Galileo’s pendulum observations inspired this development.

1. Inventor: Christiaan Huygens.
2. Year: 1656.
3. Patent Year: 1657.
4. Final Result: Huygens invented the pendulum clock.

SI Unit of Time Class 7 Questions

SI unit of time class 7 questions explain correct time units and symbols.
Second is the SI unit.
Minute and hour are larger units used in daily life.

34. What is the SI unit of time?

The SI unit of time is the second. Its symbol is s.

1. Unit Name: Second.
2. Symbol: s.
3. Correct Writing: 10 s.
4. Final Result: The SI unit of time is second.

35. What are larger units of time?

The larger units of time are minute and hour. Their symbols are min and h.

1. Minute: 1 min = 60 s.
2. Hour: 1 h = 60 min.
3. Daily Use: School periods and journeys.
4. Final Result: Minute and hour are larger time units.

36. Write the relation between second, minute and hour.

The relations are 60 s = 1 min and 60 min = 1 h. These are used in time conversion.

1. Seconds to Minute: 60 s = 1 min.
2. Minutes to Hour: 60 min = 1 h.
3. Hour to Seconds: 1 h = 3600 s.
4. Final Result: 1 h equals 3600 s.

37. How should time units be written correctly?

Time units should be written in lowercase with a space between number and unit. Symbols remain singular.

1. Correct: 5 s.
2. Correct: 10 min.
3. Correct: 2 h.
4. Final Result: Write time as number, space and unit symbol.

38. Why is writing “sec” and “hrs” incorrect?

Writing “sec” and “hrs” is incorrect because the correct symbols are s and h. Unit symbols are not made plural.

1. Second Symbol: s.
2. Hour Symbol: h.
3. Incorrect Forms: sec and hrs.
4. Final Result: Correct symbols are s, min and h.

Speed Class 7 Science Questions

Speed class 7 science questions explain how fast or slow an object moves.
Speed compares distance covered in unit time.
The SI unit of speed is metre per second.

39. What is speed?

Speed is the distance covered by an object in unit time. It tells how fast or slow the object moves.

1. Distance: Length covered.
2. Time: Duration taken.
3. Formula: Speed = distance/time.
4. Final Result: Speed measures distance covered per unit time.

40. What is the formula for speed?

The formula for speed is Speed = Total distance covered/Total time taken. It gives average speed in this chapter.

1. Distance: Total path covered.
2. Time: Total time taken.
3. Division: Distance divided by time.
4. Final Result: Speed = distance/time.

41. What is the SI unit of speed?

The SI unit of speed is metre per second. It is written as m/s.

1. Distance Unit: metre.
2. Time Unit: second.
3. Speed Unit: m/s.
4. Final Result: Speed is measured in m/s in SI.

42. What is another common unit of speed?

Another common unit of speed is kilometre per hour. It is written as km/h.

1. Distance Unit: kilometre.
2. Time Unit: hour.
3. Speed Unit: km/h.
4. Final Result: Vehicle speeds are often written in km/h.

43. How do we decide who is faster in a 100 metre race?

The runner who covers the same distance in less time is faster. In a race, all runners cover 100 metres.

1. Same Distance: 100 m.
2. Time Taken: Smaller time means higher speed.
3. Winner: Fastest runner reaches first.
4. Final Result: For same distance, less time means greater speed.

44. How do we compare speeds when distances are different?

We compare speeds by calculating distance covered per unit time. The object with higher speed is faster.

1. Distance: May differ.
2. Time: May differ.
3. Formula: Speed = distance/time.
4. Final Result: Speed compares motion for different distances.

Speed Distance Time Class 7 Questions

Speed distance time class 7 questions help students calculate motion values.
If any two values are known, the third can be found.
Students should convert units before calculation.

45. What is the relation between speed, distance and time?

The relation is speed = distance/time. It can also give distance and time.

1. Speed Formula: Speed = distance/time.
2. Distance Formula: Distance = speed × time.
3. Time Formula: Time = distance/speed.
4. Final Result: Speed, distance and time are linked by three formulas.

46. A car travels 150 m in 10 s. Find speed in m/s.

The speed is 15 m/s. Use speed = distance/time.

1. Given Data:
   Distance = 150 m
   Time = 10 s
2. Formula Used: Speed = distance/time.
3. Calculation:
   Speed = 150/10
   Speed = 15 m/s
4. Final Result: Speed = 15 m/s.

47. Convert 15 m/s into km/h.

15 m/s equals 54 km/h. Multiply m/s by 3.6.

1. Given Speed: 15 m/s.
2. Conversion: 1 m/s = 3.6 km/h.
3. Calculation: 15 × 3.6 = 54.
4. Final Result: 15 m/s = 54 km/h.

48. A runner completes 400 m in 50 s. Find speed.

The runner’s speed is 8 m/s. Use speed = distance/time.

1. Given Data:
   Distance = 400 m
   Time = 50 s
2. Formula Used: Speed = distance/time.
3. Calculation:
   Speed = 400/50
   Speed = 8 m/s
4. Final Result: Speed = 8 m/s.

49. Another runner completes 400 m in 45 s. Find speed.

The second runner’s speed is 8.89 m/s approximately. Use speed = distance/time.

1. Given Data:
   Distance = 400 m
   Time = 45 s
2. Formula Used: Speed = distance/time.
3. Calculation:
   Speed = 400/45
   Speed ≈ 8.89 m/s
4. Final Result: Speed ≈ 8.89 m/s.

50. Who has greater speed in the 400 m race and by how much?

The runner taking 45 s has greater speed by about 0.89 m/s. Compare 8.89 m/s and 8 m/s.

1. Runner 1 Speed: 8 m/s.
2. Runner 2 Speed: 8.89 m/s.
3. Difference: 8.89 − 8 = 0.89 m/s.
4. Final Result: Runner 2 is faster by 0.89 m/s.

51. A bus moves at 50 km/h for 2 h. Find distance.

The distance is 100 km. Use distance = speed × time.

1. Given Data:
   Speed = 50 km/h
   Time = 2 h
2. Formula Used: Distance = speed × time.
3. Calculation:
   Distance = 50 × 2
   Distance = 100 km
4. Final Result: Distance = 100 km.

52. A train moves at 90 km/h and covers 360 km. Find time.

The time taken is 4 h. Use time = distance/speed.

1. Given Data:
   Distance = 360 km
   Speed = 90 km/h
2. Formula Used: Time = distance/speed.
3. Calculation:
   Time = 360/90
   Time = 4 h
4. Final Result: Time = 4 h.

53. Swati cycles 3.6 km in 15 min. Find speed in m/s.

Swati’s speed is 4 m/s. Convert distance to metres and time to seconds.

1. Given Data:
   Distance = 3.6 km = 3600 m
   Time = 15 min = 900 s
2. Formula Used: Speed = distance/time.
3. Calculation:
   Speed = 3600/900
   Speed = 4 m/s
4. Final Result: Speed = 4 m/s.

54. A train travels 180 km in 3 h. Find speed in km/h and m/s.

The speed is 60 km/h or 16.67 m/s. Convert km/h to m/s by multiplying by 5/18.

1. Given Data:
   Distance = 180 km
   Time = 3 h
2. Speed in km/h:
   Speed = 180/3 = 60 km/h
3. Speed in m/s:
   60 × 5/18 = 16.67 m/s
4. Final Result: Speed = 60 km/h = 16.67 m/s.

55. How far will the same train travel in 4 h at 60 km/h?

The train will travel 240 km. Use distance = speed × time.

1. Given Data:
   Speed = 60 km/h
   Time = 4 h
2. Formula Used: Distance = speed × time.
3. Calculation:
   Distance = 60 × 4
   Distance = 240 km
4. Final Result: Distance = 240 km.

Average Speed Class 7 Questions

Average speed class 7 questions explain speed over an entire journey.
Objects in real life often speed up and slow down.
The chapter uses speed as average speed for total distance and total time.

56. What is average speed?

Average speed is total distance covered divided by total time taken. It is useful when speed changes during the journey.

1. Total Distance: Entire path covered.
2. Total Time: Entire time taken.
3. Formula: Average speed = total distance/total time.
4. Final Result: Average speed describes overall motion.

57. Why does the chapter use speed as average speed?

The chapter uses speed as average speed because objects may not move at the same speed throughout. They may move slower or faster at different times.

1. Real Motion: Speed often changes.
2. Calculation: Uses total distance and total time.
3. Term Used: Speed means average speed here.
4. Final Result: The chapter treats calculated speed as average speed.

58. A car covers 60 km, 70 km and 50 km in three hours. Find average speed.

The average speed is 60 km/h. Use total distance divided by total time.

1. Total Distance: 60 + 70 + 50 = 180 km.
2. Total Time: 3 h.
3. Formula Used: Average speed = total distance/total time.
4. Calculation: 180/3 = 60 km/h.
5. Final Result: Average speed = 60 km/h.

59. Is the car’s motion uniform if it covers 60 km, 70 km and 50 km in three equal hours?

No, the car’s motion is not uniform because it covers unequal distances in equal time intervals. Its speed changes each hour.

1. First Hour: 60 km.
2. Second Hour: 70 km.
3. Third Hour: 50 km.
4. Final Result: Unequal distances show non-uniform motion.

60. A vehicle covers 2 km in 200 s. Find average speed.

The average speed is 10 m/s. Convert 2 km into 2000 m.

1. Given Data:
   Distance = 2 km = 2000 m
   Time = 200 s
2. Formula Used: Average speed = total distance/total time.
3. Calculation:
   Average speed = 2000/200
   Average speed = 10 m/s
4. Final Result: Average speed = 10 m/s.

Uniform Motion Class 7 Questions

Uniform motion class 7 questions explain motion with constant speed along a straight line.
Such an object covers equal distances in equal time intervals.
Uniform linear motion is an idealised case in daily life.

61. What is uniform linear motion?

Uniform linear motion is motion along a straight line with constant speed. The object covers equal distances in equal time intervals.

1. Path: Straight line.
2. Speed: Constant.
3. Distance Pattern: Equal distances in equal times.
4. Final Result: Uniform linear motion has constant speed.

62. Give an example of uniform linear motion.

A train moving along a straight track at constant speed shows uniform linear motion for that part of the journey. Its speed does not change.

1. Object: Train.
2. Path: Straight track.
3. Condition: Constant speed.
4. Final Result: Train motion between B and C can be uniform.

63. Which train is uniform if it covers 20 km every 10 minutes?

The train is in uniform motion because it covers equal distances in equal time intervals. Its speed remains constant.

1. Time Interval: 10 min each.
2. Distance Each Time: 20 km.
3. Speed: Same in every interval.
4. Final Result: Equal distances in equal times show uniform motion.

64. Why is uniform linear motion called an idealisation?

Uniform linear motion is called an idealisation because daily objects rarely maintain constant speed for long. Real motion often changes due to stops and obstacles.

1. Real Traffic: Vehicles speed up and slow down.
2. Train Motion: Starts and stops.
3. Daily Life: Constant speed is uncommon.
4. Final Result: Uniform motion is rare over long distances.

Non Uniform Motion Class 7 Questions

Non uniform motion class 7 questions explain motion with changing speed.
Most daily motion is non-uniform.
Objects cover unequal distances in equal time intervals in non-uniform motion.

65. What is non-uniform linear motion?

Non-uniform linear motion is motion along a straight line in which speed keeps changing. The object covers unequal distances in equal time intervals.

1. Path: Straight line.
2. Speed: Changes.
3. Distance Pattern: Unequal distances in equal times.
4. Final Result: Non-uniform linear motion has changing speed.

66. Give an example of non-uniform motion.

A car moving in city traffic shows non-uniform motion. It slows down, stops and speeds up repeatedly.

1. Traffic Signal: Car stops.
2. Clear Road: Car speeds up.
3. Crowded Road: Car slows down.
4. Final Result: City traffic creates non-uniform motion.

67. Why is a train’s motion non-uniform near stations?

A train’s motion is non-uniform near stations because it starts slowly and later slows down to stop. Its speed changes.

1. Leaving Station: Speed increases.
2. Middle Section: Speed may become steady.
3. Approaching Station: Speed decreases.
4. Final Result: Changing speed near stations makes motion non-uniform.

68. Which motion is more common in daily life?

Non-uniform motion is more common in daily life. Vehicles, walkers and cyclists usually change speed due to conditions.

1. Bus: Stops at bus stops.
2. Car: Slows in traffic.
3. Runner: Speeds up or slows down.
4. Final Result: Most daily motion is non-uniform.

69. How can a distance-time table show non-uniform motion?

A distance-time table shows non-uniform motion when unequal distances are covered in equal time intervals. The distance increments change.

1. Equal Time: Same interval repeated.
2. Unequal Distance: Distance increments differ.
3. Conclusion: Speed changes.
4. Final Result: Changing distance increments show non-uniform motion.

NCERT Class 7 Science Chapter 8 Questions

NCERT Class 7 Science Chapter 8 questions test speed calculation, unit conversion, pendulum, and uniform motion.
Students should show formulas before numerical substitution.
These NCERT Class 7 Science Chapter 8 questions follow the 2026 exercise pattern.

70. A car travels 150 m in 10 s. Express its speed in km/h.

The car’s speed is 54 km/h. First calculate speed in m/s, then convert.

1. Given Data:
   Distance = 150 m
   Time = 10 s
2. Speed in m/s:
   Speed = 150/10 = 15 m/s
3. Conversion:
   15 m/s = 15 × 3.6 km/h
4. Final Result: Speed = 54 km/h.

71. A train travels at 25 m/s and covers 360 km. Find time taken.

The train takes 4 h. Convert speed into km/h first.

1. Given Data:
   Speed = 25 m/s
   Distance = 360 km
2. Convert Speed:
   25 m/s = 25 × 3.6 = 90 km/h
3. Formula Used: Time = distance/speed.
4. Calculation:
   Time = 360/90 = 4 h
5. Final Result: Time taken = 4 h.

72. Compare 18 m/s with 72 km/h.

18 m/s is less than 72 km/h because 18 m/s equals 64.8 km/h. The train at 72 km/h is faster.

1. Given Speed: 18 m/s.
2. Conversion: 18 × 3.6 = 64.8 km/h.
3. Comparison: 64.8 km/h < 72 km/h.
4. Final Result: 72 km/h is faster than 18 m/s.

73. Distinguish between uniform and non-uniform motion using car examples.

A car on a straight empty highway at constant speed shows uniform motion. A car in city traffic shows non-uniform motion.

1. Uniform Motion: Equal distances in equal times.
2. Highway Example: Constant speed.
3. Non-uniform Motion: Unequal distances in equal times.
4. City Example: Stops and starts.
5. Final Result: Constant speed is uniform, changing speed is non-uniform.

74. Fill the missing distance for uniform motion if distance is 8 m at 10 s.

The distance at 20 s is 16 m. Uniform motion means equal distance in each 10 s interval.

1. At 10 s: 8 m.
2. Each 10 s: Adds 8 m.
3. At 20 s: 8 + 8 = 16 m.
4. Final Result: Distance at 20 s = 16 m.

75. Fill the missing distance at 50 s for the same uniform motion.

The distance at 50 s is 40 m. The object covers 8 m every 10 s.

1. Distance per 10 s: 8 m.
2. Number of Intervals: 50/10 = 5.
3. Distance: 5 × 8 = 40 m.
4. Final Result: Distance at 50 s = 40 m.

76. A car covers 60 km, 70 km and 50 km in three hours. Is its motion uniform?

No, its motion is non-uniform because it covers unequal distances in equal one-hour intervals. Its average speed is 60 km/h.

1. Distances: 60 km, 70 km and 50 km.
2. Equal Time: 1 h each.
3. Average Speed: 180/3 = 60 km/h.
4. Final Result: Motion is non-uniform with average speed 60 km/h.

77. A train has speed 60 km/h. What distance will it cover in 4 h?

The train will cover 240 km. Use distance = speed × time.

1. Given Data:
   Speed = 60 km/h
   Time = 4 h
2. Formula Used: Distance = speed × time.
3. Calculation:
   Distance = 60 × 4
   Distance = 240 km
4. Final Result: Distance = 240 km.

78. Why can two Olympic sprinters be separated by advanced timing?

Advanced timing can measure one-hundredth or one-thousandth of a second. This helps identify winners in very close finishes.

1. Race Finish: Sprinters may seem together.
2. Timing Devices: Measure tiny intervals.
3. Result: Winner is identified accurately.
4. Final Result: Precise timing separates close race results.

Class 7 Science Chapter 8 Questions and Answers

Class 7 Science Chapter 8 questions and answers should use correct units, formulas and definitions.
Students should avoid writing sec, hrs or plural unit symbols.
These answers support quick revision for school tests.

79. What is a speedometer?

A speedometer is an instrument fitted in vehicles to display speed. It usually shows speed in km/h.

1. Vehicle: Car, bus or motorbike.
2. Quantity: Speed.
3. Common Unit: km/h.
4. Final Result: Speedometer shows vehicle speed.

80. What is an odometer?

An odometer is an instrument fitted in vehicles to measure distance travelled. It records distance in kilometres.

1. Vehicle: Car or bus.
2. Quantity: Distance.
3. Unit: kilometre.
4. Final Result: Odometer measures distance travelled.

81. Why do we usually calculate average speed?

We calculate average speed because objects often move faster and slower during a journey. Total distance and total time give overall speed.

1. Motion: Speed changes.
2. Data Needed: Total distance and total time.
3. Formula: Average speed = total distance/total time.
4. Final Result: Average speed describes a complete journey.

82. Why did ancient water clocks have limited accuracy?

Ancient water clocks had limited accuracy because water flow rate changed as water level dropped. This affected equal time measurement.

1. Water Level: Decreased with time.
2. Flow Rate: Changed.
3. Result: Accuracy reduced.
4. Final Result: Changing water flow made early water clocks less accurate.

83. What was Ghatika-yantra?

Ghatika-yantra was a sinking bowl water clock used in ancient India. Its bowl filled and sank in a fixed time.

1. Type: Water clock.
2. Action: Bowl fills and sinks.
3. Time Unit: Ghatika or ghati.
4. Final Result: Ghatika-yantra measured time with a sinking bowl.

84. What is one ghati?

One ghati was a time unit measured by Ghatika-yantra. One ghati was equal to 24 minutes.

1. Clock: Ghatika-yantra.
2. Sinking Time: 24 min.
3. Day Division: 60 ghatis made a day.
4. Final Result: One ghati equals 24 min.

85. What makes atomic clocks highly accurate?

Atomic clocks are highly accurate because they use tiny and rapid vibrations of specific atoms. They can lose only one second in millions of years.

1. Repeating Process: Atomic vibrations.
2. Precision: Extremely high.
3. Use: Advanced timekeeping.
4. Final Result: Atomic clocks are more precise than pendulum clocks.

Class 7 Science Important Links