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# NCERT Solutions for Class 7 Science Chapter 9 - Motion and Time

Last updated date: 04th Aug 2024
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Unlock the comprehensive study with Vedantu through the motion and time class 7 NCERT Solutions. This gives access to the science PDF for class 7, Chapter 9, elucidating fundamental principles crucial for understanding the subject's intricacies.

Table of Content
2. Glance on NCERT Solutions for Class 7 Science Chapter 9 Motion and Time
3. Access NCERT Solutions for Class 7 Science Chapter 9 – Motion and Time
4. Topics Covered in Class 7 Chapter 9 Science Motion and Time
5. Benefits of NCERT Solutions for Class 7 Chapter 9 - Motion and Time
6. Important Study Material for Class 7 Science Chapter 9
8. Related Important Links for Class 7 Science
FAQs

By accessing class 7 science motion and time question answers, students gain comprehensive insights into the core concepts such as motion, speed, time, and more outlined in the curriculum. These NCERT Solutions are designed by Vedantu Experts and are updated accordingly with the class 7 science syllabus.

## Glance on NCERT Solutions for Class 7 Science Chapter 9 Motion and Time

• Class 7, chapter 9 Science embarks on a fascinating journey to understand the fundamental concepts about types of motion in detail and their various aspects.

• The chapter offers the approaches important to better understanding the concept of slow and fast movement of vehicles.

• You shall learn in detail the speed and speed of different objects in motion and time class 7 PDF questions and answers.

• From motion and time class 7 questions with answers, you will also learn about a pendulum and the to-and-fro motion of a simple pendulum.

• You will not only learn to read such graphs, but you will also learn the step method of plotting a graph.

## Access NCERT Solutions for Class 7 Science Chapter 9 – Motion and Time

1. Classify the following as motion along a straight line, circular or oscillatory motion.

i) Motion of your hands while running

Ans: Oscillatory motion

During running the hands move to and fro and as this motion gets repeated after a certain time interval. Therefore it is an oscillatory motion.

ii) Motion of a horse pulling a cart on a straight road

Ans: Straight line motion

As the horse cart is moving on a straight road. Therefore motion is along the straight line.

iii) Motion of a child in a merry-go-round

Ans: Circular motion

Motion of the merry-go-round is circular. Therefore kids sitting inside it experience the circular motion.

iv) Motion of a child on a see-saw

Ans: Oscillatory motion

As the see-saw goes up and down continuously. Therefore it is an oscillatory motion.

v) Motion of the hammer of an electric bell

Ans: Oscillatory motion

When the hammer vibrates the bell it starts vibrating. It is an example of oscillatory motion.

vi) Motion of a train on a Straight Bridge

Ans: Straight line motion

The train is moving on the straight bridge. It exhibits motion of a straight line.

2. Which of the following are not correct?

i) The basic unit of time is second

Ans: Correct

SI unit of time is second.

ii) Every object moves with a constant speed

Ans: Not correct

Speed of the object is constant or variable.

iii) Distances between two cities are measured in kilometers

Ans: Correct

The distance between two cities is very large. And as a kilometer is a bigger unit therefore it is used to measure the distance between two cities.

iv) The time period of a given pendulum is not constant

Ans: Not correct

The time period depends upon the length of the thread. Therefore it will be constant for a particular pendulum.

v) The speed of a train is expressed in m/h

Ans: Not correct

The speed of the train is measured either in km/h or m/s.

3. A simple pendulum takes 32 s to complete 20 oscillations. What is the time-period of the pendulum?

Ans: The time taken to complete one oscillation is known as the time period of the pendulum.

$Time\text{ }Period\text{ }=\text{ }\dfrac{\left( Total\text{ }time\text{ }taken \right)}{\left( Number\text{ }of\text{ }Oscillations \right)}\text{ }$

Given:   $20$ oscillations taking $32s$ to complete.

$\therefore 1\text{ }oscillation\text{ }will\text{ }take\text{ }=\dfrac{\left( 32 \right)}{\left( 20 \right)\text{ }}\text{ }sec\text{ }=\text{ }1.6\text{ }second$

$\therefore \text{ }1.6s$is the time period of the pendulum.

4. The distance between two stations is$\mathbf{240}\text{ }\mathbf{km}$. A train takes$~\mathbf{4}~$hours to cover this distance. Calculate the speed of the train.

Ans: $Speed\text{ }=\text{ }\dfrac{\left( Distance\text{ }travelled \right)}{\left( Time \right)}\text{ }$

$\Rightarrow Speed=\dfrac{\left( 240\text{ }km \right)}{\left( 4h \right)}\text{ }$

$\therefore Speed=60\text{ k}m/h$

5. The odometer of a car reads $\mathbf{57},\mathbf{321}.\mathbf{0}\text{ }\mathbf{km}$when the clock shows the time $\mathbf{8}.\mathbf{30}\text{ }\mathbf{AM}$ . The odometer reading was changed to$\mathbf{57},\mathbf{336}.\mathbf{0}\text{ }\mathbf{km}$. Calculate the speed of the car in km/min during this time. Express the speed in km/h also.

Ans: Initial reading of the odometer of the car at $8:30\text{ }AM\text{ }=57321.0\text{ }km$

Final reading of the odometer of the car $8:50\text{ }AM\text{ }=\text{ }57336.0\text{ }km$

The car starts at $8:30\text{ }AM$and stops at $8:50\text{ }AM.$

$Distance\text{ }covered\text{ }by\text{ }car\text{ }=\text{ }\left( 57336\text{ - }57321 \right)\text{ }km\text{ }=\text{ }15\text{ }km$

Time taken between $08:30\text{ }AM$to $08:50\text{ }AM\text{ }=\text{ }20minutes$ $=\dfrac{20}{60}\text{ }hour$ = $\dfrac{1}{3}\text{ }hour$

So Speed in km/min

$~~~Speed\text{ }=\text{ }\dfrac{\left( Distance\text{ }travelled \right)}{\left( Time \right)}$

$\Rightarrow Speed=\dfrac{\left( 15km \right)}{\left( 20min \right)}$

$\therefore Speed=0.75km/min$

Speed in km/h

$Speed\text{ }=\dfrac{\left( Distance\text{ }travelled \right)}{\left( Time \right)}$

$\Rightarrow Speed=\dfrac{\left( 15km \right)}{\dfrac{1}{3}h}$

$\Rightarrow Speed=\dfrac{\left( 15\times 3 \right)\text{ }km}{\left( 1h \right)}$

$\therefore Speed=45km/h$

6. Salma takes $\mathbf{15}$minutes from her house to reach her school on bicycle. If the bicycle has a speed of$\mathbf{2}\text{ }\mathbf{m}/\mathbf{s}$, calculate the distance between her house and the school.

Ans : $Speed\text{ }=\text{ }2m/s$

$Time\text{ }taken\text{ }to\text{ }reach\text{ }school\text{ }=\text{ }15\text{ }min$

$\Rightarrow 15\times 60s=900\text{ }s$

$Distance=\left( Speed\text{ }x\text{ }Time \right)$

$\Rightarrow Dis\tan ce=2\times 900=1800m$

Also $1km=\text{ }1000m$

$\therefore Dis\tan ce=1800\times \dfrac{1}{1000}=1.8km.$

The distance between her house and the school is $1.8\text{ }km.$

7. Show the shape of the distance-time graph for the motion in the following cases:

i) A car moving with a constant speed.

Ans: A car moving with a constant speed covers equal distance in equal intervals of time. It will be a uniform motion.

Distance-time graph will be as below:

ii) A car parked on a side road.

Ans: A car parked on a road there is no change in the distance with the time. No motion.

Therefore the graph obtained will be parallel to x-axis.

Distance- time graph will be as below:-

8. Which of the following relations is correct?

1. $Speed\text{ }=\text{ }\left( Distance\times Time \right)$

2. $Speed\text{ }=\text{ }\left( \dfrac{Distance}{Time} \right)$

3. $Speed\text{ }=\text{ }\left( \dfrac{Time}{Distance} \right)$

4. $Speed\text{ }=\text{ }\left( \dfrac{1}{\left( Distance\times Time \right)} \right)$

Ans: Speed of an object is given by the relation:-

$Speed\text{ }=\text{ }\left( \dfrac{Distance}{Time} \right)$

9. The basic unit of speed is:

1. $k\mathbf{m}/\mathbf{min}$

2. $\mathbf{m}/\mathbf{min}$

3. $~\mathbf{km}/\mathbf{h}$

4. $\mathbf{m}/\mathbf{s}$

Ans: $\mathbf{m}/\mathbf{s}$.

The unit of distance is meter (m) and of time is second(s).

$Speed\text{ }=\text{ }\left( \dfrac{Distance}{Time} \right)$

Therefore the basic unit of speed is m/s.

10. A car moves with a speed of $\mathbf{40}\text{ }\mathbf{km}/\mathbf{h}$ for $15$ minutes and then with a speed of $\mathbf{60}\text{ }\mathbf{km}/\mathbf{h}$ for the next 15 minutes. The total  distance covered by the car is:

1. $\mathbf{100}\text{ }\mathbf{km}$

2. $\mathbf{25}\text{ }\mathbf{km}$

3. $~\mathbf{15}\text{ }\mathbf{km}$

4. $\mathbf{10}\text{ }\mathbf{km}$

Ans:  25 km

Case 1:

$Speed\text{ }=\text{ }40\text{ }km/h$

$Time=15\text{ }min=\left( \dfrac{15}{60} \right)\text{ }hour$

$Distance\text{ }\left( {{d}_{1}} \right)=Speed\times Time=40\times \left( \dfrac{15}{60} \right)=10\text{ }km$

Case 2:

$Speed=60\text{ }km/h$

$Time=15\text{ }min=\left( \dfrac{15}{60} \right)\text{ }hour$

$Distance\text{ }\left( {{d}_{2}} \right)=\left( Speed\times Time \right)=60\times \left( \dfrac{15}{60} \right)=15\text{ }km$

$Total\text{ }distance\text{ }\left( d \right)=\left( {{d}_{1}}~+\text{ }{{d}_{2}} \right)=10\text{ }km+15\text{ }km=25\text{ }km$

Therefore total distance covered by the car $=\text{ }25km.$

11. Suppose the two photographs, shown in Fig. 13.1 and Fig.13.2, had been taken at an interval of 10 seconds. If a distance of 100 meters is shown by 1 cm in these photographs, calculate the speed of the blue car.

Ans: With the help of the scale we will first measure the distance.

Suppose the distance measured is $2cm$ .

So, the distance covered $d\text{ }=2\times 100=2m$. (Because $1m=100cm$).$~Time\text{ }taken\text{ }=\text{ }10seconds.$

$Speed=\left( \dfrac{Distance}{Time} \right)=\left( \dfrac{200m}{10s} \right)=20m/s.$

Therefore the speed of the blue car $=\text{ }20m/s.$

12. Fig. 13.5 shows the distance-time graph for the motion of two vehicles A and B. Which is one of them moving faster?

Fig. 13.5

Ans: In distance – time graph speed is measured by its slope.

Vehicle A is moving faster as the slope of the graph of A is more than the slope of the graph B.

Therefore Vehicle A is moving faster

13. Which of the following distance time-graphs a truck moving with  speed which is not constant?.

Ans: (iii) as the graph is not a straight line, it keeps on changing.

This shows that the truck is moving with variable speed.

## Topics Covered in Class 7 Chapter 9 Science Motion and Time

 S.No. NCERT Science Chapter 9 Class 7 Topics 1 Slow or Fast Motion 2 Measurement of TimeUnits of time and speedMeasuring speedDistance- Time Graph

## Benefits of NCERT Solutions for Class 7 Chapter 9 - Motion and Time

With the help of the class 7 science motion and time question answers prepared by Vedantu experts, students can learn and practice the correct answers to the questions from all topics.

• It provides easy assistance and important study material to all the students struggling to find accurate answers to the time and motion class 7 questions and answers.

• The Motion and Time Class 7 PDF questions and answers are FREE to all the students, regardless of any criteria.

• Class 7, chapter 9 Science embarks on a fascinating journey to understand the fundamental concepts about types of motion in detail and their various aspects.

• Students can learn about different types of motion, including rectilinear and curvilinear motions, clarifying doubts regarding the concepts.

• They understand the difference between uniform and non-uniform motions to solve the questions easily.

• Topics like how the rate of change of distance concerning time takes place and how to calculate average speed and interpret speed-time graphs are discussed consistently to make the students learn new concepts throughout the chapter.

• Class 7, Motion and Time, offers the approaches important to understanding the concept of slow and fast movement of vehicles in a better and more precise manner.

• Students can download the motion and time class 7 PDF from Vedantu's official website.

• In motion and time class 7, you will not only learn to read such graphs, but you will also learn the step method of plotting a graph.

## Important Study Material for Class 7 Science Chapter 9

 S.No. Important Study Material Links for Class 7 Science Chapter 9 1 Class 7 Motion and Time Important Questions 2 Class 7 Motion and Time Revision Notes 3 Class 7 Motion and Time Exemplar Solutions 4 Class 7 Motion and Time Worksheets

## Conclusion

NCERT Solutions for Class 7 Science Chapter 9 - Motion and Time, provided by Vedantu, helps students understand the concepts of motion and time simply. The solutions cover important topics like types of motion, measurement of time, and related scientific principles. One crucial section focuses on explaining the various types of motion, such as circular and straight-line motion, making it easier for students to grasp these concepts. Overall, these solutions serve as a valuable resource for Class 7 students, enhancing their understanding of science and laying a foundation for more advanced learning in the future.

Dive into our FREE PDF links, which offer other chapter-wise NCERT solutions prepared by Vedantu Experts to help you understand and master fundamental scientific concepts.

## Related Important Links for Class 7 Science

 S.No. Important Links For Science Class 7 1 Science Class 7 NCERT Exemplar 2 Science Class 7 Revision Notes 3 Science Class 7 Important Questions 4 Science Class 7 Sample Papers

## FAQs on NCERT Solutions for Class 7 Science Chapter 9 - Motion and Time

1. What are Motion and Time, according to Class 7 Chapter 9 Science?

When there is a change in the position of an object concerning time, it is known as motion. In Class 7, Motion and Time, you will learn about different motions, including why some motions are fast and others are slow, speed and how it is measured,  how time is measured, and the different units of speed and time. You will also learn how to draw and understand a distance-time graph. You will solve some practical life problems too.

2. What is the unit of Time, according to class 7 Motion and Time?

Generally, the basic unit of time, that is second, is used. The bigger units of time are minute and hour. The symbol of the second is s. Though it is the most commonly used unit of time, other units are also used depending on the need. For example, no one tells their age in terms of seconds, minutes, or hours, they use year instead of that.

3. What is Speed, according to Motion and Time class 7 PDF?

Speed can be referred to as the distance covered by any moving object in a unit of time. Its basic unit is meters per second (m/s), but the speed of fast-moving vehicles is often expressed in kilometers per hour (km/hr). Fast-moving objects have high speed, i.e. they cover more distance in unit time than those of low speed which covers less distance in unit time.

4. What is the unit of speed, according to Motion and Time class 7 PDF questions and answers?

The unit of speed is distance /time, which is meters per second (m/s). Time is, of course, expressed in minutes and hours, and distance can also be expressed in other units like km, cm, mm, etc. Therefore, speed has many other units, like cm/min., km/hr, etc. These units are used only when required.

5. How do I get high marks From Motion and Time class 7 questions with answers?

To get high marks in Chapter 9 of Class 7 Science, you need to strategically study the NCERT Science book from the beginning of your session. You should also practice the NCERT solution books to get a better idea of the subject. You can download the NCERT Solution for each chapter in PDF format from Vedantu and read them offline. Practice answer writing too. These solutions are available for free on the Vedantu website and the Vedantu app and are curated by experts.

6. What's covered in the Time and Motion class 7 questions and answers?

• NCERT chapter content on motion, speed, time, and distance-time graphs.

• Solved exercises to reinforce concepts learned in class.

7. Why use the class 7 science Motion and Time question answers?

• Clear explanations: Break down complex topics into easy-to-understand steps.

• Practice problems: Help you master problem-solving skills in motion and time.

• Improved test scores: Boost your confidence by practicing with solved examples.

8. How do you access the Motion and Time class 7 Solutions?

• Search online for "NCERT Solutions Class 7 Science Chapter 9 Motion and Time" (avoid providing links in meta descriptions).

• Many websites offer free PDFs or online access.