Thursday, April 2, 2015

H C Verma solutions, Introduction to Physics, Questions for Short Answer, Chapter-1, Concepts of Physics, Part-I

Introduction to Physics

Questions for Short Answer

1. The meter is defined as the distance traveled by light in 1/299792458 second. Why did not people choose some easier number such as 1/300000000 second? Why not 1 second?      


ANSWER: The meter was historically defined in different ways. First, it was defined as ten-millionth of the distance between equator to the North pole. Scientists needed more accuracy. So next they defined the distance between two marks on the Platinum Iridium alloy bar at 0°C as one meter which was placed in a French laboratory. Next, they defined meter in a certain number of wavelengths of certain emission of Krypton86. In these standards of meter, the speed of light in vacuum came to be 299,792,458 m/s. Since the speed of light in vacuum is a universal constant, it was decided to define the meter as the distance traveled by the light in vacuum in 1/299,792,458 s. So the original meter remained the same.

          Had the people chosen an easier number such as 1/300,000,000 s, there would not have been much difference in day-to-day applications but the very very slight difference in the two standards would have made large errors in celestial measurements in modern-day. Such as the distance between the galaxies. 

        The distance traveled by the light in 1 s is very very large (299,792,458 m). Taking it as a standard meter will not be practical.     



2. What are the dimensions of:

(a) the volume of a cube of edge a,

(b) the volume of a sphere of radius a,

(c) the ratio of the volume of a cube of edge a to the volume of a sphere of radius a?      


ANSWER: (a) The volume of a cube of edge a = a³

It's dimension is = [Length³] = [L³]  

(b) The volume of a sphere of radius a = 4πa³/3

Since 4π/3 is a constant and dimensionless, hence the dimension is = [Length³] = [L³]  


(c) Since the dimensions of the volumes of the cube and the sphere are the same, hence its ratio will be dimensionless and = [M⁰L⁰T⁰]



3. Suppose you are told that the linear size of everything in the universe has been doubled overnight. Can you test this statement by measuring sizes with a meter stick? Can you test it by using the fact that the speed of light is a universal constant and has not changed? What will happen if all the clocks in the universe also start running at half the speed?      


ANSWER: No, This statement can not be tested by measuring sizes with a meter stick because the meter stick will also be get doubled. 

         Yes, the speed of light is a universal constant, the standard meter will not get changed. Hence the statement can be checked by measuring sizes with this standard.

         No, though the speed of light is constant, the distance traveled by it will get doubled in the slowed time. So the standard meter will also be get doubled, and the statement can not be checked by measuring sizes with it.    



4. If all the terms in an equation have the same units, is it necessary that they have same dimensions? If all the terms in an equation have same dimensions, is it necessary that they have the same units?      


ANSWER: Yes, all the terms will have the same dimensions because a unit has fixed dimensions.

          No, if all the terms in an equation have the same dimensions, it is not necessary that they have the same units. It is due to the fact that many different units have the same dimensions. For example, the unit of the angular speed is rad/s. Radian is dimensionless and the dimensions of the angular speed are =[M⁰L⁰T⁻¹]. The unit of frequency is Hz (cycles per second). Its dimensions are also [M⁰L⁰T⁻¹].     




5. If two quantities have the same dimensions, do they represent the same physical content?      


ANSWER: No. For example, Torque having unit of Newton-meter has dimensions = [MLT⁻¹]*[L] =[ML²T⁻¹].

The unit of energy is Joule which is also same as Newton-meter and its dimensions will also be [MLT⁻¹].   

         Both the torque and energy are different things but the same dimensions. Thus, two quantities having the same dimensions do not represent the same physical content.





6. It is desirable that the standards of units be easily available, invariable, indestructible and easily reproducible. If we use the foot of a person as a standard unit of length, which of the above features are present and which are not?      


ANSWER: The following is the qualities present or not for the foot of a person as a standard unit of length:-

1. Easily available     - Not Present (That particular person's foot will not be available everywhere).

2. Invariable             - Not present (will change with time)

3. Indestructible        - Not present

4. Easily reproducible - Not present.

 



7. Suggest a way to measure:

(a) the thickness of a sheet of paper,

(b) the distance between the sun and the moon.      


ANSWER: (a) A bunch of similar papers may be counted, then pressed tightly along the edges and the total thickness measured with a slide-calipers. This measurement divided by the number of papers will give the thickness of one sheet of the paper.

    

          (b) The distance between the sun and the moon is roughly equal to the distance between the sun and the earth. It is because the earth-moon distance (0.38 million km) is very small in comparison to the sun-earth distance (150 million km). For more accurate result with known distances of earth-moon (a) and earth-sun (b), the angle between two (α - alfa) may be measured. With two sides and included angle known, third side (Sun-moon distance - c) can be found out.
Diagram for Q-7
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Links to the Chapters





Links to Chapters:-

CHAPTER-1 - Introduction to Physics

Questions for Short Answers

OBJECTIVE - I 

OBJECTIVE - II

EXERCISES (1-10)

EXERCISES (11-19)

CHAPTER-2 - Physics, and Mathematics

Questions for Short Answers

Objective - I

Objective - II

Exercises (1 - 19)

Exercises (20 - 35)

CHAPTER-3 - Kinematics - Rest and Motion

Questions for Short Answers

Objective - I

Objective - II

Exercises - Q 1 to Q 10

Exercises - Q 11 to Q 20

Exercises - Q 21 to Q 30

Exercises - Q 31 to Q 40

Exercises - Q 41 to Q 52

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CHAPTER-4 - The Forces

Questions for Short Answers

Objective - I

Objective - II

Exercises

CHAPTER-5 - Newton's Laws of Motion

Questions for Short Answers

Objective - I

Objective - II

Exercises - Q 1 to Q 12

Exercises - Q 13 to Q 27

Exercises - Q 28 to Q 42


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CHAPTER-6 - Friction

Questions for Short Answers

Objective - I

Objective - II

Exercises - Q 1 to Q 10

Exercises - Q 11 to Q 20

Exercises - Q 21 to Q 31

CHAPTER-7 - Circular Motion

Questions for Short Answers

Objective - I

Objective - II

Exercises - Q 1 to Q 10

Exercises - Q 11 to Q 20

Exercises - Q 21 to Q 30

CHAPTER-8 - Work and Energy

Questions for Short Answers

Objective - I

Objective - II

Exercises - Q 1 to Q 10

Exercises - Q 11 to Q 20

Exercises - Q 21 to Q 30

Exercises - Q 31 to Q 42

Exercises - Q 43 to Q 54

Exercises - Q 55 to Q 64


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CHAPTER- 9 - Center of Mass, Linear Momentum, Collision

Questions for Short Answers

Objective - I

Objective - II

EXERCISES Q-1 TO Q-10

EXERCISES Q-11 TO Q-20

EXERCISES Q-21 TO Q-30

EXERCISES Q-31 TO Q-42

EXERCISES Q-43 TO Q-54

EXERCISES Q-55 TO Q-64

CHAPTER- 10 - Rotational Mechanics

Questions for Short Answers

OBJECTIVE - I

OBJECTIVE - II

EXERCISES Q-01 TO Q-15

EXERCISES Q-16 TO Q-30

EXERCISES Q-31 TO Q-45

EXERCISES Q-46 TO Q-60

EXERCISES Q-61 TO Q-75

EXERCISES Q-76 TO Q-86


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CHAPTER- 11 - Gravitation


Questions for Short Answers

OBJECTIVE - I

OBJECTIVE - II

EXERCISES Q-01 TO Q-10

EXERCISES Q-11 TO Q-20

EXERCISES Q-21 TO Q-30

EXERCISES Q-31 TO Q-39 (With Extra 40th problem)

CHAPTER- 12 - Simple Harmonic Motion 


Questions for Short Answers 


OBJECTIVE - I

OBJECTIVE-II

EXERCISES - Q-1 TO Q-10

EXERCISES - Q-11 TO Q-20

EXERCISES - Q-21 TO Q-30

EXERCISES - Q-31 TO Q-40

EXERCISES - Q-41 TO Q-50

EXERCISES - Q-51 TO Q-58 with EXTRA QUESTIONS Q-59 and Q-60 


CHAPTER- 13 - Fluid Mechanics 


Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES - Q-1 TO Q-10

EXERCISES - Q-11 TO Q-20

EXERCISES - Q-21 TO Q-30

EXERCISES - Q-31 TO Q-35



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CHAPTER- 14 - Some Mechanical Properties of Matter 


Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES - Q-1 TO Q-10

EXERCISES - Q -11 TO Q -20

EXERCISES - Q -21 TO Q -32

CHAPTER- 15 - Wave Motion and Waves on a String

Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES - Q-1 TO Q-10

EXERCISES - Q-11 TO Q-20

EXERCISES - Q-21 TO Q-30

EXERCISES - Q-31 TO Q-40

EXERCISES - Q-41 TO Q-50

EXERCISES - Q-51 TO Q-57

CHAPTER- 16 - Sound Waves

Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES - Q-1 TO Q-10

EXERCISES - Q-11 TO Q-20

EXERCISES - Q-21 TO Q-30

EXERCISES - Q-31 TO Q-40

EXERCISES - Q-41 TO Q-50

EXERCISES - Q-51 TO Q-60

EXERCISES - Q-61 TO Q-70 

EXERCISES - Q-71 TO Q-80

EXERCISES - Q-81 TO Q-89

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CHAPTER- 17 - Light Waves


CHAPTER- 18 - Geometrical Optics

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Part-II

Solutions - "Concepts of Physics" Part-II, by H C Verma

CHAPTER- 23 - Heat and Temperature

Questions for Short Answer

OBJECTIVE - I

OBJECTIVE - II

EXERCISES - Q-1 TO Q-10

EXERCISES - Q-11 TO Q-20

EXERCISES - Q-21 TO Q-34


CHAPTER- 24 - Kinetic Theory of Gases

Questions for Short Answer

OBJECTIVE - I

OBJECTIVE - II

EXERCISES - Q1 to Q10

EXERCISES - Q-11 to Q-20

EXERCISES - Q-21 to Q-30


EXERCISES - Q-31 to Q-40

EXERCISES - Q-41 to Q-50

EXERCISES - Q-51 to Q-62




CHAPTER- 25 - Calorimetry

Questions for Short Answer

OBJECTIVE - I

OBJECTIVE - II

EXERCISES - Q-1 to Q-10

EXERCISES - Q11 to Q-18 




CHAPTER- 26 - Laws of Thermodynamics

Questions for Short Answer

OBJECTIVE - I

OBJECTIVE - II

EXERCISES - Q-1 to Q-10

EXERCISES - Q-11 to Q-22




CHAPTER- 27 - Specific Heat Capacities of Gases

Questions for Short Answer

OBJECTIVE - I

OBJECTIVE - II

EXERCISES - Q-1 to Q-10 




CHAPTER- 28 - Heat Transfer


Questions for Short Answer

OBJECTIVE - I

OBJECTIVE - II

EXERCISES - Q-1 to Q-10











  

















    



























































































 





































































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