Q: Calculate the speed of a car that travels 150 metres in 10 seconds. Express your answer in km/h.

Distance = 150 mTime taken = 10 sSPeed = $\frac{\text { Distance covered }}{\text { Time taken }}$ = $\frac{150 \mathrm{~m}}{10 \mathrm{~s}}$SPeed in km/hr = 15 × $\frac{18}{5}$ = 54 km/h

Q: A runner completes 400 metres in 50 seconds. Another runner completes the same distance in 45 seconds. Who has a greater speed and by how much?

Runner 1:Distance = 400 m,Time = 50 sSPeed = $\frac{\text { Distance covered }}{\text { Time taken }}$ = $\frac{400 \mathrm{~m}}{50 \mathrm{~s}}$ = 8 m/sRunner 2:Distance = 400 m,Time = 50 sSPeed = $\frac{\text { Distance covered }}{\text { Time taken }}$ = $\frac{400 \mathrm{~m}}{45 \mathrm{~s}}$ = 8.89 m/sDifference = 8.89 – 8 = 0.89 m/sHence, speed of runner 2 is greater by approximately 0.89 m/s.

Q: A train travels at a speed of 25 m/s and covers a distance of360 km. How much time does it take?

Speed = 25 m/sDistance = 360 km = 3,60,000 mTime taken = $\frac{\text { Distance }}{\text { Speed }}$ = $\frac{3,60,0000 \mathrm{~m}}{25 \mathrm{~m} / \mathrm{s}}$= 14,400s⇒ 240 mins⇒ 4 hours

Question 1

How was time measured when there were no clocks and watches? (Page 106)

Accepted Answer

Before the invention of clocks and watches, time was measured using instruments like sundials, water clocks, hourgiasses and candle clocks.

Source: This question is from Measurement of Time and Motion, Science &mdash; Class 7, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Measurement of Time and Motion: Time, Measured, There, Clocks, Watches, Page. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 7 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberRead the question carefully and identify all parts before answering.
Use the terminology specific to this subject and chapter.
Review the textbook content for this chapter before attempting questions.
Practice writing concise, well-structured answers within time limits.
Related Questions from Measurement of Time and MotionQ10: Data for an object covering distances in different intervals of time are given in the following...
Q11: A vehicle moves along a straight line and covers a distance of 2 km. In the first 500 m, it moves...
Q12: Which type of motion is more common in daily life—uniform or non-uniform? Provide three examples...
Q14: A vehicle moves along a straight line and covers a distance of 2 km. In the first 500 m, it moves...
Q2: For races covering the same distance, we can tell who was faster by measuring time. But how can we...
Practice more questions from Measurement of Time and Motion &mdash; Science, Class 7 CBSE

Question 2

For races covering the same distance, we can tell who was faster by measuring time. But how can we tell that when comparing races for different distances? (Page 112)

Accepted Answer

If races cover the same distance, we can tell who was faster by measuring the time taken.

Source: This question is from Measurement of Time and Motion, Science &mdash; Class 7, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Measurement of Time and Motion: Races, Covering, Same, Distance, Tell, Faster. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 7 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberRead the question carefully and identify all parts before answering.
Use the terminology specific to this subject and chapter.
Review the textbook content for this chapter before attempting questions.
Practice writing concise, well-structured answers within time limits.
Related Questions from Measurement of Time and MotionQ10: Data for an object covering distances in different intervals of time are given in the following...
Q11: A vehicle moves along a straight line and covers a distance of 2 km. In the first 500 m, it moves...
Q12: Which type of motion is more common in daily life—uniform or non-uniform? Provide three examples...
Q14: A vehicle moves along a straight line and covers a distance of 2 km. In the first 500 m, it moves...
Q3: I once watched a part of marathon on a straight road stretch. I noticed that some people seemed to...
Practice more questions from Measurement of Time and Motion &mdash; Science, Class 7 CBSE

Question 3

I once watched a part of marathon on a straight road stretch. I noticed that some people seemed to be running at the same speed during that distance while some people would speed up or slow down. How were their motion different? (Page 116)

Accepted Answer

People who run at. the same speed have uniform motion, but those who speed up or slow down have non-uniform motion.NCERT Class 7 Science Chapter 8 Question Answer Measurement of Time and Motion (Exercise)

Question 4

Calculate the speed of a car that travels 150 metres in 10 seconds. Express your answer in km/h.

Accepted Answer

Distance = 150 mTime taken = 10 sSPeed = $\frac{\text { Distance covered }}{\text { Time taken }}$ = $\frac{150 \mathrm{~m}}{10 \mathrm{~s}}$SPeed in km/hr = 15 × $\frac{18}{5}$ = 54 km/h

Question 5

A runner completes 400 metres in 50 seconds. Another runner completes the same distance in 45 seconds. Who has a greater speed and by how much?

Accepted Answer

Runner 1:Distance = 400 m,Time = 50 sSPeed = $\frac{\text { Distance covered }}{\text { Time taken }}$ = $\frac{400 \mathrm{~m}}{50 \mathrm{~s}}$ = 8 m/sRunner 2:Distance = 400 m,Time = 50 sSPeed = $\frac{\text { Distance covered }}{\text { Time taken }}$ = $\frac{400 \mathrm{~m}}{45 \mathrm{~s}}$ = 8.89 m/sDifference = 8.89 – 8 = 0.89 m/sHence, speed of runner 2 is greater by approximately 0.89 m/s.

Question 6

A train travels at a speed of 25 m/s and covers a distance of360 km. How much time does it take?

Accepted Answer

Speed = 25 m/sDistance = 360 km = 3,60,000 mTime taken = $\frac{\text { Distance }}{\text { Speed }}$ = $\frac{3,60,0000 \mathrm{~m}}{25 \mathrm{~m} / \mathrm{s}}$= 14,400s⇒ 240 mins⇒ 4 hours

Question 7

Data for an object covering distances in different intervals of time are given in the following table. If the object is in uniform motion, fill in the gaps in the table.

Accepted Answer

Answer:
In uniform motion, object covers equal distances in equal intervals of time. Hence, the speed of an object remains constant throughout the motion.

Time (s)
0
10
20
30
40
50
60
70

Distance (m)
0
8
16
24
32
40
48
56

The object covers 8 m in every 10 seconds. Hence, the speed of an object remains constant at 0.8 m/s throughout the motion.

Question 8

Distinguish between uniform and non-uniform motion using the example of a car moving on a straight highway with no traffic and a car moving in city traffic.

Accepted Answer

Uniform motion: If an objects covers equal distances in equal distance in equal intervals of time, its motion is said to be uniform. A car moving on a straight highway with no traffic is an example of uniform motion.Non-uniform motion: If an object covers unequal distances in equal interval of time, its motion is said to be non-uniform. A car moving in a traffic is an example of nonuniform motion.

Question 9

Data for an object covering distances in different intervals of time are given in the following table. If the object is in uniform motion, fill in the gaps in the table.
Time (s)
0
10
20
30
50
70
Distance (m)
0
8
24
32
40
56

Accepted Answer

In uniform motion, object covers equal distances in equal intervals of time. Hence, the speed of an object remains constant throughout the motion.Time (s)010203040506070Distance (m)08162432404856The object covers 8 m in every 10 seconds. Hence, the speed of an object remains constant at 0.8 m/s throughout the motion.

Question 10

A vehicle moves along a straight line and covers a distance of 2 km. In the first 500 m, it moves with a speed of 10 m/s and in the next 500 m, it moves with a speed of 5 m/s. With what speed should it move the remaining distance so that the journey is complete in 200 s? What is the average speed of the vehicle for the entire journey?Answer:GivenTotal distance = 2 km = 2000 m,Total time = 200Step 1: Time taken to cover the first 500 mTime = $\frac{\text { Distance }}{\text { Speed }}$ = $\frac{500}{10}$ = 50 s

Accepted Answer

Answer:
Do it yourself. Activity 8.2: Let us Experiment (Pages 109-110) Answer:
Do it yourself. Activity 8.3: Let Us Identify (Page 112) Look at the wall clock shown in Fig. 8.9 carefully. What is the smallest interval of time you can measure with it?
[Measurement of Time and Motion Class 7 Questions and Answers Science Chapter 8-1]
• One second is the smallest interval of time that we can measure using this clock. Activity 8.4: Let Us Calculate (Pages 114-115) Table 8.2: Finding the speed of trains Name of the railway station nearest to your place of stay Delhi.

Name of the train
Name of the next station
Distance till the next station (km)
Time taken till the next station(N
Speed of the train between these two stations (km/h)

Vande Bharat
Ambala Cantt.
214
2h 12 min
97.27

Shatabdi Express
Aligarh
158
1h 30 min
105.33

Tejas Express
Kota
465
2h
232.5

Shan-e-Punjab
Panipat
99
1h 25 min
69.88

Question 11

Which type of motion is more common in daily life—uniform or non-uniform? Provide three examples from your experience to support your

Accepted Answer

Answer:In our daily life, most motions are nonuniform because object do not move at the same speed all the time. Their speed changes due to factors like traffic, rough or uneven roads and other obstacles.Examples:• Travelling in a bus on an uneven road• Playing cricket• Walking through a crowded market

Question 12

A vehicle moves along a straight line and covers a distance of 2 km. In the first 500 m, it moves with a speed of 10 m/s and in the next 500 m, it moves with a speed of 5 m/s. With what speed should it move the remaining distance so that the journey is complete in 200 s? What is the average speed of the vehicle for the entire journey?

Accepted Answer

GivenTotal distance = 2 km = 2000 m,Total time = 200Step 1: Time taken to cover the first 500 mTime = $\frac{\text { Distance }}{\text { Speed }}$ = $\frac{500}{10}$ = 50 sStep 2: Time taken to cover the next 500 mTime = $\frac{500}{10}$ = 100 sStep 3: Remaining distance = 2000 – 1000 = 1000 mRemaining time = 200 – 150 = 50 sStep 4: Speed required to cover the remaining 1000 mSpeed = $\frac{1000}{50}$ = 20 m/sStep 5: Average speed = $\frac{Total distance}{Total time taken }$ = $\frac{2000}{200}$ = 10 m/sClass 7 Measurement of Time and Motion Question Answer (Activities)Activity 8.1: Let Us Construct (Page 107)Answer:Do it yourself.Activity 8.2: Let us Experiment (Pages 109-110)Answer:Do it yourself.Activity 8.3: Let Us Identify (Page 112)Look at the wall clock shown in Fig. 8.9 carefully. What is the smallest interval of time you can measure with it?• One second is the smallest interval of time that we can measure using this clock.Activity 8.4: Let Us Calculate (Pages 114-115)Table 8.2: Finding the speed of trains Name of the railway station nearest to your place of stay Delhi.Name of the trainName of the next stationDistance till the next station (km)Time taken till the next station(NSpeed of the train between these two stations (km/h)Vande BharatAmbala Cantt.2142h 12 min97.27Shatabdi ExpressAligarh1581h 30 min105.33Tejas ExpressKota4652h232.5Shan-e-PunjabPanipat991h 25 min69.88