NCERT Solutions for Class 7 Science Motion and Time Question Answers - FREE PDF Download
Unlock the comprehensive study with Vedantu through the motion and time class 7 Science 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
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.
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?
\[Speed\text{ }=\text{ }\left( Distance\times Time \right)\]
\[Speed\text{ }=\text{ }\left( \dfrac{Distance}{Time} \right)\]
\[Speed\text{ }=\text{ }\left( \dfrac{Time}{Distance} \right)\]
\[Speed\text{ }=\text{ }\left( \dfrac{1}{\left( Distance\times Time \right)} \right)\]
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:
\[k\mathbf{m}/\mathbf{min}\]
\[\mathbf{m}/\mathbf{min}\]
\[~\mathbf{km}/\mathbf{h}\]
\[\mathbf{m}/\mathbf{s}\]
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:
\[\mathbf{100}\text{ }\mathbf{km}\]
\[\mathbf{25}\text{ }\mathbf{km}\]
\[~\mathbf{15}\text{ }\mathbf{km}\]
\[\mathbf{10}\text{ }\mathbf{km}\]
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
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.
Motion and time class 7 questions with answers will help you revise your NCERT concepts, facilitating a better understanding of the appropriate answering pattern. So, it will help you to score well in exams.
Important Study Material for Class 7 Science Chapter 9
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.
NCERT Solutions for Class 7 Science - Other Chapter-wise Links for FREE PDF
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.
Important Related Links for NCERT Class 7 Science
Access these essential links for NCERT Class 7 Science, offering comprehensive solutions, study guides, and additional resources to help students master language concepts and excel in their exams.
FAQs on NCERT Solutions for Class 7 Science Chapter 9 Motion and Time
1. What are the main types of motion explained in NCERT Solutions for Class 7 Science Chapter 9?
Chapter 9 "Motion and Time" covers three major types of motion:
- Rectilinear (straight-line) motion: Movement along a straight path, such as a car on a straight road.
- Circular motion: Movement along a circular path, for example, a merry-go-round.
- Oscillatory motion: Repetitive to-and-fro motion, like a pendulum or a vibrating electric bell.
2. How do the NCERT Solutions for Class 7 Science Chapter 9 explain the calculation of speed?
The solutions teach that Speed is calculated as the ratio of distance travelled to the time taken, using the formula:
Speed = Distance ÷ Time.
The basic SI unit is meters per second (m/s), but kilometers per hour (km/h) is also commonly used for larger distances, as explained in solved questions following CBSE patterns.
3. What strategy is provided in NCERT Solutions for solving distance-time graph questions?
NCERT Solutions for Class 7 Science Chapter 9 guide students to:
- Plot distance on the Y-axis and time on the X-axis
- Interpret slopes: a straight (non-horizontal) line means constant speed; a horizontal line indicates no motion
- Use step-by-step approaches for plotting and analysis, as per the latest CBSE exam methodology
4. According to NCERT Solutions, what is the difference between uniform and non-uniform motion?
Uniform motion occurs when an object covers equal distances in equal intervals of time, resulting in a straight-line distance-time graph. Non-uniform motion happens when the distance covered per unit time varies; its graph is curved or irregular. The solutions provide multiple examples and solved cases for both types, matching CBSE answer formats.
5. How are measurement units for speed and time emphasized in the Class 7 Science Chapter 9 solutions?
The NCERT Solutions stress that the SI unit of time is the second (s) and the SI unit of speed is meters per second (m/s). Larger practical units like minutes, hours, and kilometers per hour (km/h) are used for real-life applications, as illustrated in solved textbook exercises.
6. What are common mistakes students should avoid when answering motion and time problems, according to expert NCERT Solutions guidance?
Common errors to avoid include:
- Confusing units (e.g., mixing hours with seconds without conversion)
- Misidentifying the motion type
- Incorrect plotting of values on the distance-time graph
7. Why is the concept of 'average speed' important in Class 7 Chapter 9 NCERT Solutions?
Average speed is the total distance travelled divided by the total time taken, especially relevant in non-uniform motion cases. The chapter stresses its calculation and significance in understanding real-life movement, directly supporting CBSE question trends.
8. How is the time period of a pendulum described in the Motion and Time Class 7 NCERT Solutions?
The time period is defined as the time taken for one complete oscillation by a pendulum. Questions in the chapter teach the formula: Time Period = Total Time Taken ÷ Number of Oscillations, with practical numericals relevant for CBSE 2025–26 exams.
9. How does the NCERT Solution approach help students prepare for Class 7 Science Motion and Time exam questions?
Solutions provide:
- Step-by-step, CBSE-aligned answers
- Practice with calculations and graphs
- Clarification of definitions and units
- Discussion of frequently asked concepts and errors
10. What should be done if different units of measurement are given in a Motion and Time problem in Class 7 Science?
Always convert all values to standard units (distance in meters or kilometers; time in seconds or hours) before applying any formula. The NCERT Solutions emphasize unit consistency for accurate answers as per CBSE norms.
11. What makes the NCERT Solutions for Class 7 Science Chapter 9 useful for building analytical skills?
By practicing calculation-based and graph-based questions, students:
- Sharpen logical reasoning
- Enhance data interpretation
- Increase accuracy in choosing methods and units
12. How are motion graphs misinterpreted and what does NCERT guidance recommend?
Common misinterpretations include confusing a flat (horizontal) line as motion at constant speed instead of no motion, or misreading slopes. The NCERT Solutions provide detailed instructions and multiple examples to avoid such errors, as per CBSE standards.
13. What if an object changes speed during the time observed—how is this shown in NCERT Solutions for Class 7 Science Chapter 9?
If an object's speed isn’t constant, its distance-time graph will not be a straight line but a curve. The solutions explain how to recognize and plot variable speed motion graphically, an essential skill for scoring in CBSE exams.
14. Can you explain why precise unit conversion is important in CBSE Class 7 Science Motion and Time questions?
Precise unit conversion is crucial because CBSE marking schemes penalize errors in units. Differences such as seconds vs. minutes, or kilometers vs. meters, can change the final answer completely. NCERT Solutions teach students how to handle conversions systematically for reliable results.
15. How do NCERT Solutions for Class 7 Science Chapter 9 address higher-order thinking questions (HOTs) on motion and time?
HOTs are addressed by including conceptual applications, such as comparing two moving objects using distance-time graphs and calculating average speeds under varying conditions. These go beyond memorization, engaging students in critical analysis in line with latest CBSE 2025–26 exam expectations.
