CBSE Class 7 Science Exemplar Chapter 13: Motion and Time NCERT Solutions

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NCERT Solutions PDF Class 7 PDF

This chapter, Motion and Time, delves into fundamental concepts of physics relevant to Class 7 students. The NCERT Solutions cover the measurement of time, understanding periodic and non-periodic motions, and the relationship between distance, time, and speed. It explains how various natural phenomena and instruments like simple pendulums are used to measure time intervals. The solutions also guide students on plotting and interpreting distance-time graphs, which are crucial for visualizing and analyzing motion. By working through these solutions, students will gain a clear understanding of how to quantify motion and time, essential skills for further scientific exploration and exam preparation.

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Quick info

BoardCBSE
ClassClass 7
SubjectScience Exemplar
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 13

Chapter summary

Chapter 13 of the CBSE Class 7 Science Exemplar focuses on Motion and Time. The NCERT Solutions provided here explain the principles of measuring time using periodic events and instruments. It differentiates between various types of motion and clarifies how to represent motion using distance-time graphs. The solutions cover the interpretation of these graphs to determine speed and understand motion patterns, aiding students in grasping key physics concepts.

Learning outcomes

  • Understand the concept of periodic and non-periodic motion.
  • Identify suitable methods and instruments for measuring time intervals.
  • Explain how a simple pendulum can be used to measure time.
  • Interpret distance-time graphs to understand the motion of objects.
  • Calculate speed from distance and time data.
  • Differentiate between different types of clocks and their measurement capabilities.

Topics covered

Paper topics

  • Measurement of Time
  • Periodic Motion
  • Non-periodic Motion
  • Simple Pendulum
  • Clocks
  • Distance-Time Graph
  • Speed
  • Uniform Motion
  • Non-uniform Motion

Important topics

  • Measurement of Time using Periodic Events
  • Interpreting Distance-Time Graphs
  • Calculating Speed from Distance and Time
  • Distinguishing Periodic vs. Non-periodic Motion
  • Capabilities of Different Clocks

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Questions and Solutions

Multiple Choice Questions

1. Which of the following cannot be used for measurement of time?

A leaking tap.

Simple pendulum.

Shadow of an object during the day.

Blinking of eyes.

Solution: The correct option is (d) Blinking of eyes.

Explanation: Blinking of eyes is not a periodic phenomenon because eyes do not blink at a fixed or regular interval of time. Periodic phenomena, which occur at regular intervals, are used for measuring time. Examples of periodic phenomena used for time measurement include the swing of a simple pendulum or the movement of shadows cast by the sun.

Multiple Choice Questions

2. Two clocks A and B are shown in Figure 13.1. Clock A has an hour and a minute hand, whereas clock B has an hour hand, minute hand as well as a second hand. Which of the following statement is correct for these clocks?

A time interval of 30 seconds can be measured by clock A.

A time interval of 30 seconds cannot be measured by clock B.

Time interval of 5 minutes can be measured by both A and B.

Time interval of 4 minutes 10 seconds can be measured by clock A.

Solution: The correct statement is (c) Time interval of 5 minutes can be measured by both A and B.

Explanation: Clock A, having only an hour and a minute hand, cannot measure time intervals involving seconds accurately. Clock B, which includes a second hand, can measure time intervals in seconds. Therefore, a 30-second interval cannot be measured by clock A. A 5-minute interval, however, can be easily measured by both clocks as it falls within their minute-counting capabilities. A 4 minutes 10 seconds interval cannot be measured by clock A because it lacks a second hand.

Multiple Choice Questions

3. Two students were asked to plot a distance-time graph for the motion described by Table A and Table B.

Table A

Distance moved (m)01020305040
Time (minutes)0246108

Table B

Distance moved (m)0510152520
Time (minutes)012354

Figure 13.2 shows a distance-time graph.

Solution: The question asks to plot distance-time graphs for the given data in Table A and Table B. The provided Figure 13.2 appears to be a sample graph, possibly related to one of the tables, but the specific question requires plotting based on the data.

Plotting for Table A:

Points to plot: (0,0), (2,10), (4,20), (6,30), (10,50), (8,40).

Note: The data for 8 minutes (40m) seems out of sequence with the increasing trend. If plotted as given, the graph will show a decrease after 10 minutes.

Plotting for Table B:

Points to plot: (0,0), (1,5), (2,10), (3,15), (5,25), (4,20).

Note: Similar to Table A, the data for 4 minutes (20m) is out of sequence.

Interpretation: A distance-time graph helps visualize an object's motion. A straight line indicates uniform speed, while a curved line indicates non-uniform speed. The slope of the line represents the speed of the object.

Common mistakes

  • Confusing periodic and non-periodic motions.
  • Incorrectly plotting points on a distance-time graph.
  • Misinterpreting the scale on a distance-time graph.
  • Assuming all blinking or tapping is periodic.
  • Errors in calculating speed from distance and time.

Revision tips

  • Review the definitions of periodic and non-periodic motion with examples.
  • Practice plotting distance-time graphs from given data tables.
  • Understand how to read and interpret information from a distance-time graph.
  • Memorize the formula for speed and practice calculations.
  • Compare the capabilities of different types of clocks for measuring time.

Practice MCQs

Q1. Which of the following is NOT a reliable method for measuring time?

Q2. A clock that has only an hour and a minute hand can accurately measure:

Q3. What is the primary limitation of Clock A (hour and minute hand only) for time measurement?

Q4. A distance-time graph shows a straight line passing through the origin. This indicates:

Frequently asked questions

What is the main concept covered in CBSE Class 7 Science Exemplar Chapter 13?

Chapter 13, Motion and Time, covers the fundamental concepts of measuring time, understanding different types of motion (periodic and non-periodic), and analyzing motion using distance-time graphs.

How are NCERT Solutions for Chapter 13 helpful for students?

These solutions provide clear explanations and rewritten answers to the textbook questions, helping students understand concepts like time measurement, speed calculation, and graph interpretation, which are crucial for exams.

Can a simple pendulum be used to measure any time interval?

A simple pendulum can be used to measure time intervals, especially for shorter durations. Its regular swing is a periodic motion that can be counted to determine elapsed time.

What does a straight line on a distance-time graph represent?

A straight line on a distance-time graph represents an object moving with uniform speed. This means the object covers equal distances in equal intervals of time.

Why is blinking of eyes not used for measuring time?

Blinking of eyes is not a periodic phenomenon; it does not occur at fixed intervals. Therefore, it is unreliable for accurate measurement of time.

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