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Exercise-2B Motion in One Dimension Concise ICSE Class-9 Selina Publishers Chapter-2 .Step By Step ICSE Selina Concise Solutions of Chapter-2 Motion in One Dimension  with Exercise-2(A), Exercise-2(B) and Exercise-2(C) including Numerical and MCQ Questions Solved Visit official Website CISCE for detail information about ICSE Board Class-9.

 Board ICSE Publications Selina Publication Subject Physics Class 9th Chapter-2 Motion in One Dimension  Exe-2(b) Book Name Concise Topics Solution of Exercise-2(A),  MCQ-2(A),  Numericals-2(A),   Exercise-2(B), MCQ-2(B), Numericals-2(B),    Exercise-2(C),  MCQ-2(C) ,  Numericals-2(C), Academic Session 2021-2022

## Exercise-2B Motion in One Dimension Concise ICSE Class-9 Selina Publishers Chapter-2

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Exercise-2(A),  MCQ-2(A),  Numericals-2(A),

Exercise-2(B),  MCQ-2(B),  Numericals-2(B),

Exercise-2(C),  MCQ-2(C) ,  Numericals-2(C),

Note :-  Before Viewing Selina Concise Physics Solutions of Chapter-2 Motion in One Dimension Class-9 . Read the whole chapter carefully and Solved all example of Exercise-2 Motion in One DimensionClass-9

Focus on Chapter-2 Motion in One Dimension in Scalar and vector quantities, distance, speed, velocity acceleration.  Motion in One Dimension in graph of distance – time and speed- time.  Equations of uniformly accelerated motion with derivations in Motion in One Dimension .

### EXERCISE-2(B) Selina Physics Solutions Chapter-2 Motion in One Dimension

Page 47

#### Question 1

For the motion with uniform velocity, how is the distance travelled related to the time?

#### Answer 1

Distance is directly proportional to time,

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#### Question 2

What information about the motion of a body is obtained from the displacement-time graph?

#### Answer 2

From displacement-time graph, the nature of motion (or state of rest) can be understood. The slope of this graph gives the value of velocity of the body at any instant of time, using which the velocity-time graph can also be drawn.

#### Question 3

(a)What does the slope of a displacement-time graph represent?

(b)Can displacement-time sketch be parallel to the displacement axis? Give a reason to your answer.

#### Answer 3

(a) Slope of a displacement-time graph represents velocity.

(b) The displacement-time graph can never be parallel to the displacement axis because such a line would mean that the distance covered by the body in a certain direction increases without any increase in time, which is not possible.

#### Question 4

Draw a displacement-time graph for a boy going to school with uniform velocity.

#### Question 5 (Exercise-2B Motion in One Dimension Concise)

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State how the velocity-time graph can be used to find (i) The acceleration of a body, (ii) The distance traveled by the body in a given time and (iii) The displacement of the body in a given time.

#### Answer 5

(i) The slope of the velocity-time graph gives the value of acceleration.

(ii) The total distance travelled by a body in a given time is given by the area enclosed between the velocity-time graph and X-axis (without any sign).

(iii) The displacement of a body in a given time is given by the area enclosed between the velocity-time graph and X-axis (with proper signs).

#### Question 6

What can you say about the nature of motion of a body if its displacement-time graph is

(a) A straight line parallel to the time axis?

(b) A straight line inclined to the time axis with an acute angle?

(c) A straight line inclined to the time axis with an obtuse angle?

(d) A curve.

#### Answer 6

(a) There is no motion, the body is at rest.

(b) It depicts that the body is moving away from the starting point with uniform velocity.

(c) It depicts that the body is moving towards the starting point with uniform velocity.

(d) It depicts that the body is moving with variable velocity.

#### Question 7

Fig. 2.33 shows the displacement-time graph of two vehicles A and B moving along a straight road. Which vehicle is moving faster? Give reason.

#### Answer 7

Vehicle A is moving with a faster speed because the slope of line A is more than the slope of line B.

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Page 48

#### Question 8

State the type of motion represented by the following sketches in Fig. 2.34 (a) and (b).

Give an example of each type of motion.

#### Answer 8

(a) Fig. 2.34 (a) represents uniformly accelerated motion. For example, the motion of a freely falling object.

(b) Fig. 2.34 (b) represents motion with variable retardation. For example, a car approaching its destination.

#### Question 9 (Exercise-2B Motion in One Dimension Concise)

Draw a velocity-time graph for a body moving with an initial velocity u and uniform acceleration a. Use this graph to find the distance travelled by the body in time t.

#### Answer 9

In this graph, initial velocity = u

Velocity at time t = v

Let acceleration be ‘a’

Time = t

Then, distance travelled by the body in t s = area between the v-t graph and X-axis

Or distance travelled by the body in t s = area of the trapezium OABD

= (1/2) × (sum of parallel sides) × (perpendicular distance between them)

= (1/2) × (u + v) × (t)

= (u + v)t /2

#### Question 10

What does the slope of velocity-time graph represent?

#### Answer 10

The slope of the velocity-time graph represents acceleration.

#### Question 11

Fig. 2.35 shows the velocity-time graphs for two cars A and B moving in the same direction. Which car has greater acceleration? Give reasons to your answer.

#### Answer 11

Car B has greater acceleration because the slope of line B is more than the slope of line A.

#### Question 12

Draw  the shape of the velocity-time graph for a body moving with (a) Uniform velocity and (b) Uniform acceleration.

#### Answer 12

Velocity-time for a body moving with uniform velocity and uniform acceleration.

#### Question 13 Motion in One Dimension

The velocity-time graph for a uniformly retarded body is a straight line inclined to the time axis with an obtuse angle. How is retardation calculated from the velocity-time graph?

#### Answer 13

retardation is calculated by finding the negative slope.

#### Question 14

figure 2.36 shows the displacement – time graph for four bodies A, B C and D. In each case state what information do you get about the acceleration (zero, positive or negative).

#### Answer 14

For body A: The graph is a straight line. So, the slope gives constant velocity. Hence, the acceleration for body A is zero.

For body B: The graph is a straight line. So, the slope gives constant velocity. Hence, the acceleration for body B is also zero.

For body C: The slope of the graph is decreasing with time. Hence, the acceleration is negative.

For body D: The slope of the graph is increasing with time. Hence, the acceleration is positive.

#### Question 15

Draw a graph for acceleration against time for a uniformly accelerated motion. How can it be used to find the change in speed in a certain interval of time?

#### Answer 15

The area enclosed between the straight line and time axis for each interval of time gives the value of change in speed in that interval of time

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