Class 11th

Q.2.1 Fill in the blanks

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2.1

(a) The volume of a cube of side 1 ${c m}^{3}$ is equal to $10^{- 6} m^{3}$

The volume of the cube = 1 cm * 1 cm * 1 cm = 1 cm³

1 cm3 = 1 * 10^-6 m³

(b) The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to1.25 * 10⁴ (mm)²

The surface area of a solid cylinder = 2? r (r+)h, where r = 2.0 cm = 20 mm, h = 10 cm = 100 mmSurface area = 2 * 22/7 * 20 * (100 +20) ${m m}^{2}$ = 1.51 * $10^{4}$ ${m m}^{2}$

(c) A vehicle moving with a speed of 18 km h^–1 covers 5 m in 1 s

Vehicle speed = 18 km/h = 18000/3600 m/s = 5 m/s

(d) The relative density of lead is 11.3. Its density is 11.3 g cm^–3 or 11.3 * 10³.kg m^–3.

Relative density o

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2.1

(a) The volume of a cube of side 1 ${c m}^{3}$ is equal to $10^{- 6} m^{3}$

The volume of the cube = 1 cm * 1 cm * 1 cm = 1 cm³

1 cm3 = 1 * 10^-6 m³

(b) The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to1.25 * 10⁴ (mm)²

The surface area of a solid cylinder = 2? r (r+)h, where r = 2.0 cm = 20 mm, h = 10 cm = 100 mmSurface area = 2 * 22/7 * 20 * (100 +20) ${m m}^{2}$ = 1.51 * $10^{4}$ ${m m}^{2}$

(c) A vehicle moving with a speed of 18 km h^–1 covers 5 m in 1 s

Vehicle speed = 18 km/h = 18000/3600 m/s = 5 m/s

(d) The relative density of lead is 11.3. Its density is 11.3 g cm^–3 or 11.3 * 10³.kg m^–3.

Relative density or Specific gravity = Density of the subject / density of water

Density of water = 1 gm/cc= 10^-3 / 10^-6

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A calorie is a unit of heat (energy in transit) and it equals about 4.2 J where 1J = 1 kg m² s^–2. Suppose we employ a system of units in which the unit of mass equals α kg, the unit of length equals β m, the unit of time is γ s. Show that a calorie has a magnitude 4.2 α ^–1 β ^–2 γ ² in terms of the new units.

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Q.2.3 A calorie is a unit of heat (energy in transit) and it equals about 4.2 J where 1J = 1 kg m² s^–2. Suppose we employ a system of units in which the unit of mass equals α kg, the unit of length equals β m, the unit of time is γ s. Show that a calorie has a magnitude 4.2 α ^–1 β ^–2 γ ² in terms of the new units.

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Class 11th Oscillations

Matter can exist in three primary states:

Solids: Definite shape and volume, incompressible, particles tightly packed.

Liquids: Definite volume but no definite shape, slightly compressible, particles less tightly packed than in solids.

Gases: Neither definite shape nor volume, highly compressible, particles far apart.

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1.14 “It is more important to have beauty in the equations of physics than to have them agree with experiments”. The great British physicist P. A. M. Dirac held this view. Criticize this statement. Look out for some equations and results in this book which strike you as beautiful.

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1.14 One of the reasons of not so much popularity amongst masses about Physics is it is full of equations and symbols. I tend to agree with Scientist Dirac. But when one look at the simple equations, they are really beautiful. For example – W = mg, F = pA, E = mc² etc.

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1.13 Though the law gives women equal status in India, many people hold unscientific views on a woman's innate nature, capacity and intelligence, and in practice give them a secondary status and role. Demolish this view using scientific arguments, and by quoting examples of great women in science and other spheres; and persuade yourself and others that, given equal opportunity, women are on par with men.

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1.13 Both men and women are of equal caliber. Since nature has given extra strength to women to bear child, they can endure immense physical and mental pain than men. Women have a keen eye for perfection, hence more and more women are being employed in present industries. Earlier the professions like fighter pilots, CEO, security personnel, cab drivers, assemblers, in factories, even football referee were believed to be male dominated, but we can see the presence of women in these fields also.

Following is the list of some of the women, who have excelled in various fields.

Indira Gandhi
Margaret Thatcher
Mother Teresa
Indra Nouie
Kalpana Cha

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1.12 India has had a long and unbroken tradition of great scholarship — in mathematics, astronomy, linguistics, logic and ethics. Yet, in parallel with this, several superstitious and obscurantist attitudes and practices flourished in our society and unfortunately continue even today — among many educated people too. How will you use your knowledge of science to develop strategies to counter these attitudes?

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1.12 Mass awareness is the only tool. By using different communication platforms like Radio, TV, Social media, Movies etc. people can be made aware. The superstitious belief can be explained in a scientific way and they can be made aware.

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1.11 Science, like any knowledge, can be put to good or bad use, depending on the user.

Given below are some of the applications of science. Formulate your views on whether The particular application is good, bad or something that cannot be so clearly Categorized:

(a) Mass vaccination against small pox to curb and finally eradicate this disease from the population. (This has already been successfully done in India)

(b) Television for eradication of illiteracy and for mass communication of news and ideas

(c) Prenatal sex determination

(d) Computers for increase in work efficiency

(e) Putting artificial satell

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