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A famous relation in physics relates ‘moving mass’ m to the ‘rest mass’ m0 of a particle in term of its speed v and the speed of light, c [ This relation first arose as a consequence of special relativity due to Albert Einstein]. A boy recalls the relation almost correctly but forgets where to put the constant c. He writes: m= m_0/〖(1- v^2)〗^(1/2) NCERT Solution

A famous relation in physics relates ‘moving mass’ m to the ‘rest mass’ m0 of a particle in term of its speed v and the speed of light, c [ This relation first arose as a consequence of special relativity due to Albert Einstein]. A boy recalls the relation almost correctly but forgets where to put the constant c. He writes: m= m_0/〖(1- v^2)〗^(1/2)

Physics Q Phobia January 27, 2019

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A book with many error contains four different formulas for the displacement y of a parties undergoing a certain periodic motion : (a) y = a sin 2π t/T (b) y = a sin vt (c) y = (a/T) sin t/a (d) y = (a √2 (sin 2π t/T + cos 2π t/T) (a = maximum displacement of the particle, v = speed of the particle, T = time-period of motion), Rule out the wrong formulas on dimensional grounds. NCERT Solution

A book with many error contains four different formulas for the displacement y of a parties undergoing a certain periodic motion : (a) y = a sin 2π t/T (b) y = a sin vt (c) y = (a/T) sin t/a (d) y = (a √2 (sin 2π t/T + cos 2π t/T) (a = maximum displacement of the particle, v = speed of the particle, T = time-period of motion), Rule out the wrong formulas on dimensional grounds.

Physics Q Phobia January 27, 2019

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A physical quantity P is related to four observables a, b, c and das follows: P = a3b 2 / √(c ) d The percentage error of measurement in a, b, c and d are 1% 3% 4% and 2%, respectively. What is the percentage error in the quantity p? If the value of p calculated using the above relation turns out to be 3.763, to what value should you around off the result? NCERT Solution

A physical quantity P is related to four observables a, b, c and das follows: P = a3b 2 / √(c ) d The percentage error of measurement in a, b, c and d are 1% 3% 4% and 2%, respectively. What is the percentage error in the quantity p? If the value of p calculated using the above relation turns out to be 3.763, to what value should you around off the result?

Physics Q Phobia January 27, 2019

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The mass of a box measured by a grocer’s balance is 2.300 kg. Two gold pieces of masses 20.15 g and 20.17 g are added to a box. What is (a) the total mass of a mass of the box, (b) the difference in the masses of the pieces to correct significant figures? NCERT Solution

The mass of a box measured by a grocer’s balance is 2.300 kg. Two gold pieces of masses 20.15 g and 20.17 g are added to a box. What is (a) the total mass of a mass of the box, (b) the difference in the masses of the pieces to correct significant figures?

Physics Q Phobia January 27, 2019

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The length, breadth and thickness of a rectangular sheet of metal are 4.234 m, 1.005 m, and 2.01 cm respectively. Give the area and volume of the sheet to correct significant figures. NCERT Solution

The length, breadth and thickness of a rectangular sheet of metal are 4.234 m, 1.005 m, and 2.01 cm respectively. Give the area and volume of the sheet to correct significant figures.

Physics Q Phobia January 27, 2019

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State the number of significant figures in the following: 0.007 m^2 (b) 2.64 x 10^24 kg (c) 0.2370 g cm^(-2) (d) 6.320 J (e) 6.032 N m^(-2) (f ) 0.0006032 m^2 NCERT Solution

State the number of significant figures in the following: 0.007 m^2 (b) 2.64 x 10^24 kg (c) 0.2370 g cm^(-2) (d) 6.320 J (e) 6.032 N m^(-2) (f ) 0.0006032 m^2

Physics Q Phobia January 25, 2019

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The photograph of a house occupies an area of 1.75 cm2 on a 35 mm slide. The slide is projected on to a screen, and the area of the house on the screen is 1.55 m2. What is the linear magnification of the projector-screen arrangement? NCERT Solution

The photograph of a house occupies an area of 1.75 cm2 on a 35 mm slide. The slide is projected on to a screen, and the area of the house on the screen is 1.55 m2. What is the linear magnification of the projector-screen arrangement?

Physics Q Phobia January 25, 2019

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Answer the following: (a) You are given a thread and a metre scale. How will you estimate the diameter of the thread? (b) A screw gauge has a pitch of 1.0 mm and 200 divisions on the circular scale. Do you think it is possible to increase the accuracy of the screw gauge arbitrarily by increasing the number of divisions on the circular scale? (c) The mean diameter of a thin brass rod is to be 2 measured by vernier callipers. Why is a set of 100 measurements of the diameter expected to yield a more reliable estimate than a set of 5 measurements only? NCERT Solution

Answer the following: (a) You are given a thread and a metre scale. How will you estimate the diameter of the thread? (b) A screw gauge has a pitch of 1.0 mm and 200 divisions on the circular scale. Do you think it is possible to increase the accuracy of the screw gauge arbitrarily by increasing the number of divisions on the circular scale? (c) The mean diameter of a thin brass rod is to be 2 measured by vernier callipers. Why is a set of 100 measurements of the diameter expected to yield a more reliable estimate than a set of 5 measurements only?

Physics Q Phobia January 25, 2019

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A Student measure the thickness of a human hair by looking at it through a microscope of magnification 100.He measure 20 observations and finds that the average width of the hair in the field of view of the microscope is 3.5 mm. What is the estimate on the thickness of air? NCERT Solution

A Student measure the thickness of a human hair by looking at it through a microscope of magnification 100.He measure 20 observations and finds that the average width of the hair in the field of view of the microscope is 3.5 mm. What is the estimate on the thickness of air?

Physics Q Phobia January 25, 2019

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Which of the following is the most precise device for measuring length? (a) A vernier callipers with 20 divisions on the sliding scale (b) A screw gauge of pitch 1 mm and 100 division’s sliding scale on the circular scale (c) An optical instrument that can measure length to within a wavelength of light NCERT Solution

Which of the following is the most precise device for measuring length? (a) A vernier callipers with 20 divisions on the sliding scale (b) A screw gauge of pitch 1 mm and 100 division’s sliding scale on the circular scale (c) An optical instrument that can measure length to within a wavelength of light

Physics Q Phobia January 25, 2019

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A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the sun and the Earth in term of the new unit if light takes 8 min and 20 s to cover this distance? NCERT Solution

A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the sun and the Earth in term of the new unit if light takes 8 min and 20 s to cover this distance?

Physics Q Phobia January 24, 2019

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Explain this statement clearly: “To call a dimensional quantity ‘large’ or ‘small’ is meaningless without specifying a standard for meaning.” In view of this, reframe the following statement wherever necessary: a) Atoms are very small objects b) A het plane moves with great speed c) The mass of Jupiter is very large d) The air inside this room contain a large number of molecules e) A protons is much more massive than an electron f) The speed of sound is much smaller than the speed of light. NCERT Solution

Explain this statement clearly: “To call a dimensional quantity ‘large’ or ‘small’ is meaningless without specifying a standard for meaning.” In view of this, reframe the following statement wherever necessary: a) Atoms are very small objects b) A het plane moves with great speed c) The mass of Jupiter is very large d) The air inside this room contain a large number of molecules e) A protons is much more massive than an electron f) The speed of sound is much smaller than the speed of light.

Physics Q Phobia January 24, 2019

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A calorie is a unit of heat or energy and it equals about 4.2 J where 1 J = 1 kg m2 s-2 Suppose we employee a system of units in which the unit of mass equal α kg, the unit of length equal 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 term of the new units. NCERT Solution

A calorie is a unit of heat or energy and it equals about 4.2 J where 1 J = 1 kg m2 s-2 Suppose we employee a system of units in which the unit of mass equal α kg, the unit of length equal 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 term of the new units.

Physics Q Phobia January 24, 2019

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Fill in the blanks (a) 1 kg m3 = …… g cm2 a-2 (b) 1 m = …….. ly (c) 3.0 m s-2 = …….. km h-2 (d) G = 6.67 x 10-11 N m2 (kg)-2 = …… (cm)3 s-2 g-1. NCERT Solution

Fill in the blanks (a) 1 kg m3 = …… g cm2 a-2 (b) 1 m = …….. ly (c) 3.0 m s-2 = …….. km h-2 (d) G = 6.67 x 10-11 N m2 (kg)-2 = …… (cm)3 s-2 g-1.

Physics Q Phobia January 24, 2019

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Fill in the blanks (a) The volume of a cube of side 1 cm is equal to …….. m3. (b)The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to ….. (mm)2 (c) A vehicle moving with a speed of 18 km h-1 cover …… m in 1 s. (d) The relative density of lead is 11.3. Its density is …. G cm-3 or ….. Kg m-3. NCERT Solution

Fill in the blanks (a) The volume of a cube of side 1 cm is equal to …….. m3. (b)The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to ….. (mm)2 (c) A vehicle moving with a speed of 18 km h-1 cover …… m in 1 s. (d) The relative density of lead is 11.3. Its density is …. G cm-3 or ….. Kg m-3.

Physics Q Phobia January 24, 2019

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