# Measurements and Experimentation Exe-1C Short Answer Physics Class-9 ICSE Selina Publishers

Measurements and Experimentation Exe-1C Measurement of Time and Simple Pendulum Short / Long Answer Type for Class-9 ICSE Concise Physics. There is the solutions of short Answer type Questions of your latest textbook which is applicable in 2023-24 academic sessionVisit official Website CISCE for detail information about ICSE Board Class-9.

## Measurements and Experimentation Exe-1 C Measurement of Time and Simple Pendulum Short Answer

(ICSE Class – 9 Physics Concise Selina Publishers)

 Board ICSE Class 9 Subject Physics Writer / Publication Concise selina Publishers Chapter-1 Measurements and Experimentation Exe – 1 C Measurement of Time and Simple Pendulum Topics Solution of Exe-1(C) Short / Long Answer Type Questions Academic Session 2023-2024

### Exe-1 C Measurement of Time and Simple Pendulum Short Answer Type

Ch-1 Measurements and Experimentation Physics Class-9 ICSE Concise

Page 27

#### Question 1. What is a simple pendulum? Is the pendulum used in a pendulum clock as a simple pendulum? Give reason to your answer.

Answer : A simple pendulum is a heavy point mass (known as bob) suspended from a rigid support by a mass less and in extensible string.

No, the pendulum used in pendulum clock is not a simple pendulum because the simple pendulum is an ideal case. We cannot have a heavy mass having the size of a point and string having no mass.

### Exe-1 C Measurement of Time and simple Pendulum Short Answer Type

Ch-1 Measurements and Experimentation Physics Class-9 ICSE Concise

Page 28

#### Question 3. Name two factors on which the time period of a simple pendulum depends. Write the relation for the time period in terms of the above named factors.

Answer : Two factors on which the time period of a simple pendulum depends are

(i) Length of pendulum (l)

(ii) Acceleration due to gravity (g)

T=2π √L /√g

#### Question 4. How do you measure the time period of a given pendulum? Why do you note the time for more than one oscillation?

Answer : Measurement of time period of a simple pendulum:

(i) To measure the time period of a simple pendulum, the bob is slightly displaced from its mean position and is then released. This gives a to and fro motion about the mean position to the pendulum.

(ii) The time ‘t’ for 20 complete oscillations is measured with the help of a stop watch.

(iii)Time period ‘T’ can be found by dividing ‘t’ by 20.

To find the time period, the time for the number of oscillations more than 1 is noted because the least count of stop watch is either 1 s or 0.5 s. It cannot record the time period in fractions such as 1.2 or 1.4 and so on.

#### Question 5. Two simple pendulums A and B have lengths 1.0 m and 4.0 m, respectively, at a certain place. Which pendulum will make more oscillations in 1 min? Explain your answer

Answer : Pendulum A will take more time (twice) in a given time because the time period of oscillation is directly proportional to the square root of the length of the pendulum. Therefore, the pendulum B will have a greater time period and thus making lesser oscillations.

#### Question 6. State how does the time period of a simple pendulum depend on (a) length of pendulum, (b) mass of bob, (c) amplitude of oscillation and (d) acceleration due to gravity.

(a) The time period of oscillations is directly proportional to the square root of the length of the pendulum.

(b) The time period of oscillations of simple pendulum does not depend on the mass of the bob.

(c) The time period of oscillations of simple pendulum does not depend on the amplitude of oscillations.

(d) The time period of oscillations of simple pendulum is inversely proportional to the square root of acceleration due to gravity.

## Long Answer Type Questions of Exe-1 C Measurement of Time and Simple Pendulum

Ch-1 Measurements and Experimentation Physics Class-9 ICSE Concise

Page 28

#### Question 1. How does the time period (T) of a simple pendulum depend on its length (l)? Draw a graph showing the variation of T2 with l. How will you use this graph to determine the value of g (acceleration due to gravity)?

Answer : The time period of a simple pendulum is directly proportional to the square root of its effective length.

From this graph, the value of acceleration due to gravity (g) can be calculated as follows.

The slope of the straight line can be found by taking two points P and Q on the straight line and drawing normals from these points on the X- and Y-axis, respectively. Then, the value of T2 is to be noted at a and b, the value of l at c and d. Then,

— : End of Measurements and Experimentation Exe-1 C Measurement of Time Short/ long  Answer Type  Solutions :–

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