NCERT Solutions for Class 7 Science Chapter 13 : Motion and Time

Q:

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

A:

Among the given distance-time graphs, following graph shows the movement of a truck with speed which is not constant:

It is so because in this graph vehicle is not covering equal distances in equal intervals of time.

Q:

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 metres is shown by 1 cm in these photographs, calculate the speed of the blue car.

A:

The steps to be followed are as follows:

  1. Find the distance travelled by blue car in photographs by measuring distance taking mid-points of car in following manner:

(Here, distance may vary in centimeters due to difference in the size of photographs taken. So, follow only the method for finding right answer, which may vary.)

  1. According to the question, 1 cm is equivalent to 100 m.

Therefore, distance travelled = 0.5 cm x 100m = 50m

  1. Speed = distance travelled / time taken

Therefore, speed = 50m / 10s = 5 m/s

Q:

The basic unit of speed is: (i) km/min (ii) m/min (iii) km/h (iv) m/s

A:

Correct option is (iv).

Explanation: Speed is the distance traveled per unit of time. The standard unit of distance is metre (m) and standard unit of time is second (s).

Q:

A:

Correct option is (ii).

Explanation: Speed is the distance traveled per unit of time.

Q:

Fig.13.15 shows the distance-time graph for the motion of two vehicles A and B. Which one of them is moving faster?

A:

Among the vehicles, vehicle A is moving faster than B. It is so because A has travelled greater distance in shorter period of time in comparison to that of vehicle B. Vehicle B has moved lesser distance in greater period of time as depicted in graph.

Q:

A car moves with a speed of 40 km/h for 15 minutes and then with a speed of 60 km/h for the next 15 minutes. The total distance covered by the car is: (i) 100 km (ii) 25 km (iii) 15 km (iv) 10 km

A:

Average speed of car = (40 km/h + 60 km/h)/2 = 50 km/h

Total distance travelled = speed × total time taken = 50 km/h × (½) h = 25 km/h

                                                                    

Q:

Show the shape of the distance-time graph for the motion in the following cases: (i) A car moving with a constant speed. (ii) A car parked on a side road.

A:

  1. The shape of the distance-time graph for the motion of car with constant speed will be as follows:

  1. The shape of the distance-time graph for the motion of car parked on a side road will be as follows:

Q:

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

A:

Time taken by Salma = 15 min = 15 × 60 s = 900 s

Speed of bicycle = 2 m/s

Let the distance between school and house be x m

Distance travelled = time taken × speed

∴ Distance, x = 900 s × 2 m/s = 1800 m = 1.8 km

Q:

The odometer of a car reads 57321.0 km when the clock shows the time 08:30 AM. What is the distance moved by the car, if at 08:50 AM, the odometer reading has changed to 57336.0 km? Calculate the speed of the car in km/min during this time. Express the speed in km/h also.

A:

Q:

The distance between two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.

A:

Q:

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

A:

Q:

Which of the following are not correct?
(i) The basic unit of time is second.
(ii) Every object moves with a constant speed.
(iii) Distances between two cities are measured in kilometres.
(iv) The time period of a given pendulum is constant.
(v) The speed of a train is expressed in m/h.

A:

Following statements are not correct:

(ii) Every object moves with a constant speed.

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

Q:

Classify the following as motion along a straight line, circular or oscillatory motion:
(i) Motion of your hands while running.
(ii) Motion of a horse pulling a cart on a straight road.
(iii) Motion of a child in a merry-go-round.
(iv) Motion of a child on a see-saw.
(v) Motion of the hammer of an electric bell.
(vi) Motion of a train on a straight bridge.

A:

 

S.No.

Straight Line Motion

Circular Motion

Oscillatory Motion

1.

Motion of a horse pulling a cart on a straight road.

Motion of a child in a merry-go-round.

Motion of your hands while running.

2.

Motion of a train on a straight bridge.

 

Motion of a child on a see-saw.

3.

 

 

Motion of the hammer of an electric bell.

Benefits of NCERT Solutions

Following are some of the benefits of using NCERT Solutions by Extramarks.

1. The NCERT solutions for class 7 are prepared keeping in mind the necessary rules and format issued by the CBSE board thus providing students much-needed preview of the exam pattern of questions and preview of the exam that they are going to face during the final exams.

2. The students can be sure about the quality of the solutions as they are committed by highly experienced and expert teachers. These teachers have years of experience and they make sure that there is no mistake committed when preparing the solutions.

3. The NCERT 7 solutions are provided for the questions that are most likely to appear in the exam thus improving the efficiency of the students by helping them prepare for the important parts of the syllabus.

Tips & Strategies for Class 7 Exam Preparation

1. Start your revision early so you can revise well and grasp all the difficult concepts.

2. Organize your study time by making a timetable as it will help you manage your time accordingly.

3. Take mock tests and solve sample papers as they will help you learn time management during the exam and make you familiar with the exam pattern.

4. Take regular breaks, look after yourself by sleeping properly and eating well.

5. Know your exam well, explore the mock tests, and practice sample papers as much as you can.

Why Choose Extramarks CBSE Class 7 Study Materials?

1. The solutions have been compiled keeping in mind the purpose of scoring high marks in exams thus they have everything that the students need to prepare for exams.
2. The NCERT solutions for class 7 are designed in a clear and simple language complete with diagrams so that the students understand the subject well.
3. The NCERT 7 solutions are accurate thus improving their reliability.
4. The solutions are designed by expert and experienced teachers that help in removing all doubts out of the solutions and improving the credibility of the answers.

Frequently Asked Questions

product
Is class 7 Math NCERT book sufficient for prepare for the exams?

Yes, the NCERT book has been designed keeping in mind the pattern of paper that will be presented in the exam to students. The NCERT book is sufficient to study for the exam as it has everything related to the exam and contains all information out of which the questions will be asked in the exam. But if you want to prepare a little bit extra, we suggest that you go through the NCERT class 7 solutions.

When to refer to NCERT solutions for class 7th?

When you are studying the NCERT book for math and other subjects for your class 7 exams, refer to the NCERT class 7 solutions simultaneously so you can see where you are going wrong and what are you getting right in your exercises’ attempt.

Why are the NCERT solutions important for Class 7th?

The class 7th is very crucial as it is among the major middle school classes during which the child’s base is formed in math and science and even in other subjects like English. Thus, it is students must study smartly in this class and ace their exams while getting all the help they need from the NCERT 7 solutions given by Extramarks.

Can I rely on the NCERT solutions for class 7 Math at Extramarks to perform well in the annual exam?

Yes, absolutely. The NCERT solutions provided by Extramarks for class 7 are eloquent and elaborate at best and are thus useful for students studying for the final exams of class 7. The students will have many questions and doubts regarding the NCERT solutions for class 7 and this is why the solutions have been elaborated well to help students understand the answers to exercises.

Do you provide NCERT solutions for Class 7 Math for free?

Yes, the NCERT solutions for Math and other subjects for class 7 are available for free from Extramarks.

Start Your
7-Days Free Trial
and experience it yourself
Start Trial
Play StoreApp Store
Flying Girl
A subscription
that’s worth your
money
Get the best classroom experience on
India’s leading learning platform

Get
in touch

Have a query about our services?
Get in touch with us and we will
guide you through a new world of
redefined learning

Union
Get OTP
Submit