We can estimate the area of the head. Question 2. Access the answers to hundreds of Measurement questions that are explained in a way that's easy for you to understand. question_answer42) What is common between bar and torr? Show that a calorie has a magnitude 4.2  α-1 β-2 γ2 in terms of the new units. Answer: Volume of one hydrogen atom = 4/3 πr3 (volume of sphere) Question 2. This was the actual motivation behind the discovery of radar in World War II. Answer: The measured (nominal) volume of the block is, How much will 5J measure in this new system? .•. Long Answer Type Questions = 4/3 x 3.14 x (0.5 x 10-10) m3 = 5.23 x 10-31 m3 Study Guide Unit 1 Math, Measurement, and Scientific Practices 1. Are we justified in calling length a fundamental quantity, if another physical quantity (temperature) has to be specified in choosing a standard? The solution drops spread into a thin, large and roughly circular film of molecular thickness on water surface. Find the Earth’s average density to appropriate significant figures. (Take the size of hydrogen molecule to be about 1 A.) Since the least number of decimal places is 2 so the difference in masses to the correct significant figures is 0.02 g. Question 2. So, the nuclear mass density is independent of mass number. Error in 1 second=0.02/100 x 365 x 24 x 60 x 60 What is a unit? = Dimensions of R.H.S. Question 2. Played 79 times. (c) The mass of Jupiter is very large compared to that of the earth. Answer:  No, 1 A = 10-10 m | What is the distance between the Sun and the Earth in terms of the new unit if light takes 8 min and 20 s to cover this distance? A unit is defined as a convention to define an amount of physical property in a specific system of units. Answer: Question 5. = 1920″ = 1920 x 4.85 x 10-6 rad [1″ = 4.85 x 10-6 rad] Question 2. 1. [T] = [M L-1 T-2]a [M L-3]b [M L2 T-2]c  Equating powers of M, L and T on both sides, Obtain Dirac’s number, given that the desired number is proportional to mp-1 and me-2. Answer:  No, it is not possible. 21. 17. r = 2.1 and Ar = ± 0.5 Practice the multiple choice questions to test understanding of important topics in the chapters. Media Can a quantity have different dimensions in different systems of units? Answer:  In order to find out the accuracy of the given equation we shall compare the dimensions of T and rh ρg/2cos θ. III. Mean value, M mean = $$\frac{2.52+2.53+2.51+2.49+2.54}{5}$$ The unit of length convenient on the nuclear scale is afermi: I f=10-15 m. Nuclear sizes obey roughly the following empirical relation: It is known that the period T of a magnet of magnetic moment M vibrating in a uniform magnetic field of intensity B depends upon M, B and I where I is the moment of inertia of the magnet about its axis of oscillations. = 7.38 x 1010 m Which quantity should be measured more accurately and why? Obtain the dimensional formula for coefficient of viscosity. Which material is used in the liquid type of fuse? Suggest a distance corresponding to each of the following order of length: (i) ${{10}^{7}}\mathbf{m}$ (ii) $\mathbf{1}{{\mathbf{0}}^{\mathbf{4}}}\mathbf{m}$ (Hi) ${{10}^{2}}\mathbf{m}$ (iv) $\mathbf{1}{{\mathbf{0}}^{\mathbf{-}}}^{\mathbf{3}}\mathbf{m}$ (v) $\mathbf{1}{{\mathbf{0}}^{\mathbf{-6}}}\mathbf{m}$ (vi) $\mathbf{1}{{\mathbf{0}}^{\mathbf{-14}}}\mathbf{m}$. How much is this distance in terms of parsecs? Why do we treat length, mass and time as basic or fundamental quantities in mechanics? (A) Hydrometer. Answer: Question 12. 20. It is known that the refractive index ‘μ’ of the material of the prism is given by a=0,b=+(1/2) and c=+(1/2). Sample Papers question_answer20) If the units of force and length each are doubled, then how many times would the unit of energy be affected? What does LASER stand for? NR is a function of the density of the liquid r, its average speed is v and the coefficient of viscosity of the liquid is h. If NR is given directly proportional to d (the diameter of the pipe), (b) We know that least count = Pitch/number of divisions on circular scale When number of divisions on circular scale is increased, least count is decreased. 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? | Answer: Question 7. The measurement of any physical quantity is expressed in terms of a number and a specific unit.Measurement = Quantity × UnitExample: 1. Answer: N m-1 s2 is nothing but SI unit of mass i.e., the kilogram. Compare it with the average mass density of a sodium atom obtained in Exercise 2.27. NEET Physics : Units and Measurement. Question 2. Precise measurements of physical quantities are a need of science. 12. neet solved physics mcq, Units, dimension and measurement ,solved 275 mcq for IIT, AIIMS, NEET, MCAT and State board CET examinations gneet TOPIC : Units, dimension and measurement Number of questions are 276 What is the distance in km of a quasar from which light takes 3.0 billion years to reach us? = 4/3 πr3 = 4/3 π [r0 A1/3]3 = 4/3 πr03A 2 years ago. Parallax angle subtended by 1 parsec distance at this basis = 2 second (by definition of parsec). Answer: Here, θ=2000 Mass of earth = — x 3.142 x (6.37 x 106)3 x 5.517 x 103 kg 3. Physical Quantities consist of a _____ and its _____. Dimensions of L.H.S. Multiple choice Questions and Answers on Measurement and Instrumentation Answer: According to principle of homogenity of dimensional equations, NCERT Solutions for Class 11 Physics Chapter 2 Units and Measurements are part of Class 11 Physics NCERT Solutions. 3.2 x 104 μL. (b) MKS system CGS system,2. If 'slap' times speed equals power, what will be the dimensional equation for 'slap'? Think of different examples in modem science where precise measurements of length, time, mass etc., are needed. The velocity v of a particle depends on time t as: $\upsilon =A{{t}^{2}}+Bt+C$ where $\upsilon$ is in m/s and t in second. Name four units used in the measurement of extremely short distances. Volume of hydrogen molecule = 4/3 πr3 Units & Measurements MCQ Test - Set 03 GK Units Edit G.K. The Sun is a hot plasma (ionized matter) with its inner core at a temperature exceeding 107 K, and its outer surface at a temperature of about 6000 K. At these high temperatures, no substance remains in a solid or liquid phase. (a) atoms are very small objects CBSE XI Science Physics Units and Measurement The sun's angular diameter is measured to be 1920'' ( 1920 seconds) . Here we have covered Important Questions on Units and Measurements for Class 11 Physics subject. Now Vg/VH=22.4 x 10-3/3.1548 x 10-7 =7.1 x 104 (a = maximum displacement of the particle, v = speed of the particle, T = time-period of motion)Rule out the wrong formulas on dimensional grounds. (b) The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to ……..(mm)2. | On solving these equations, we find that All Chapter 2 - Units and Measurement Exercises Questions with Solutions to help you to revise complete Syllabus and boost your score more in examinations. If its coincidence with the age of the universe were significant, what would this imply for the constancy of fundamental constants? Units and Measurements's Previous Year Questions with solutions of Physics from JEE Main subject wise and chapter wise with solutions. question_answer50) The mean value of period of oscillation of a simple pendulum in an experiment is$\mathbf{2}.\mathbf{825}\text{ }\mathbf{s}$. If the percentage errors in measurements of a, b and c are ± 1%, ±2% and ± 1.5% respectively, then calculate the maximum percentage error in value of x obtained. The percentage errors in m, D and l are 1%, 1.5% and 0.5%. (b) a screw gauge of pitch 1 mm and 100 divisions on the circular scale. Note in Eqn. Can there be a physical quantity that has no units and no dimensions? question_answer4) Do $\overset{\text{o}}{\mathop{\text{A}}}\,$ and AU stand for the same unit of length? What is N m-1 s2 equal to? Privacy Policy In fact its dimensional formula is [mol-1]. Q. Name two physical quantities having the dimensions $[M{{L}^{2}}{{T}^{-2}}]$. Answer:  About 1 in 1012 to 1013 s. Question 9. question_answer21) The velocity v of a particle depends on time t as: $\upsilon =A{{t}^{2}}+Bt+C$ where $\upsilon$ is in m/s and t in second. CGS System In this system, the unit of length is centimetre, the unit of mass is gram and the unit of time is second. D=b/20=3 x 1011/2 x 4.85 x 10-6 m Answer: Here n1 = 60 W. Obviously, the physical quantity is power whose dimensional formula is [M1 L2 T3-]. Answer: SONAR stands for ‘sound navigation and ranging’. What is the difference between mN, Nm and nm? Also, wherever you can, give a quantitative idea of the precision needed. What is the linear magnification of the projector-screen arrangement? Question 22. Answer:  As magnification, m =thickness of image of hair/ real thickness of hair = 100 Physics notes for class 9th chapter 1 PDF consist of the solved Review Questions and Conceptual Questions. Volume of Sun = 4/3πr3 x 3.14 x (7 x 108)3  = 1.437 x 1027 m3 question_answer41) If the velocity of light is taken as the unit of velocity and one year as the unit of time, what must be the unit of length? Each correct answer fetches 3 marks, while each incorrect answer has a penalty of 1 mark (-1 mark). Also explore over 10 similar quizzes in this category. answer choices . Answer: 1 a.m.u. = A/(4/3πr03A) = 3/4πr03 Copyright © 2007-2020 | Explain this common observation clearly: If you look out of the window of a fast moving train, the nearby trees, houses etc., seem to move rapidly in a direction opposite to the train’s motion, but the distant objects (hill tops, the Moon, the stars etc.) Angle, specific gravity, Poisson’s ratio and Strain are four examples of dimensionless quantities. Answer:  Here l = (25.2 ± 0.1) cm (a) The volume of a cube of side 1 cm is equal to…………m3. = 28.38 x 1024 m = 2.8 x 1025 m or 2.8 x 1022 km. get Justify. These Multiple Choice Questions with answers are very important for competitive exams like IIT, JEE, NEET, AIIMS, JIPMER etc. Current Affairs The first system, in which unit of power is 1 watt, is SI system in which M1 = 1 kg,L1 = 1 m and T1= ls in second system, M2 = 100 g, L2 = 20 cm and T2 = 1 min = 60 s. Question 24. neet solved physics mcq, Units, dimension and measurement ,solved 275 mcq for IIT, AIIMS, NEET, MCAT and State board CET examinations gneet TOPIC : Units, dimension and measurement Number of questions are 276 If d be the distance of Moon from the earth, the time taken by laser signal to return after reflection at the Moon’s surface. As p = M/V,                .’. The velocity v of a particle at time t is given by where a, b and c are constants, The dimensions of a, b and c are respectively: Answer. Similarly the upper limit can also be calculated as follows. (a) 1 (b)2 (c)3 (d)5 Videos (d) G = 6.67 x 10-11 N m2 (kg)-2 = …. (e) We can determine the volume of the class-room by measuring its length, breadth and height. Volume = (4.234 x 1.005) x (2.01 x 10-2) = 8.55289 x 10-2 = 0.0855 m3. In an experiment with common balance the mass of a body is found to 2.52g, 2.53g, 2,51g, 2.49g and 2.54g in successive measurements. Question 19. By practising these questions, students get thorough with the important topics of this chapter. Long Answer Type Questions. [2007 OL] Answer:  Given that l = 4 cm and Al = 0.1 cm (least count of the metre scale) here l is the distance between the legs of the spherometer. To express these in terms of F, A and V, we must express, M, L and T in terms of these new ‘fundamental’ quantities. Unit 1: Physical Quantities, Units and Measurements DRAFT. Get help with your Measurement homework. Answer:  As the Reynold’s number NR depends on density p, average speed v and coefficient of viscosity η, then let us say, Question 11. ft is required to find the volume of a rectangular Mock. (b) Least count of screw gauge =Pitch/No. All Chapter 2 - Units and Measurement Exercises Questions with Solutions to help you to revise complete Syllabus and … km h-2 What is done to minimize this error? Which of the formulae for kinetic energy (K) given below can you rule out on the basis of dimensional arguments (m stands for the mass of the body) : (a) $K={{m}^{2}}{{\upsilon }^{3}}$       (b) $K=\left( 1/2 \right)m{{\upsilon }^{2}}$ (c) $~K=ma$           (d) $~K=\text{ }(\mathbf{3}\text{ }/16)m{{\upsilon }^{2}}$ (e) $K=(\mathbf{1}/\text{ 2})m{{\upsilon }^{2}}+\text{ }ma$. stand for same length? Answer:  As we know, 1 light year = 9.46 x 1015 m Answer: No, since density = Mass/Volume. What is it called? | N=-D n2-n1/x2-x1 All Do You Known ? If no, name three physical quantities which are dimensionless. Answer: We first note that the dimension of I are [ML2]. 29. These properties of a laser light can be exploited to measure long distances. Check if your guess is correct from the following data: mass of the Sun = 2.0 x 1030 kg, radius of the Sun = 7.0 x 108 m. Which of the following is the most precise device for measuring length: As the film is extremely thin, this thickness t may be considered to be the size of one molecule of oleic acid i.e., t is the molecular diameter of oleic acid. 23. What are the five steps of the scientific method (in order) and an explanation of each? Answer:  We know that the usual dimensions of Y are [MLT–2]/[L2] i.e.,[M L-2T-2] Ncert Solutions question_answer2) How is SI a coherent system of units? The SI unit of energy is$J=kg{{m}^{2}}{{s}^{-2}},$that of speed $\upsilon$ is $\mathbf{m}{{\mathbf{s}}^{-\mathbf{1}}}$and acceleration a is $\mathbf{m}{{\mathbf{s}}^{-\mathbf{2}}}$. (d) the air inside this room contains a large number of molecules Answer: Given angular diameter θ = 35.72= 35.72 x 4.85 x 10-6 rad Answer: Which is a bigger unit-light year or parsec? You did well on the units and conversions quiz. .•. The radius of curvature of a concave mirror measured by spherometer is given by R =l2/6h + h/2.The values of l and h are 4 cm and 0.065 cm respectively. System as 6.67 x 10-8dyne cm2 g-2, find the earth is 1.496 × 10^11m earth ’ s.. Same order of magnitude on a system having 100 g, 20 cm and 1 minute the! Better in the Measurement of any physical quantity that has no units and Measurements CBSE 11! Suresh again got confused because he never used these units devices, paper sizes and other triva. Surface tension of a number and units and measurements questions and answers area of ( 2500 ±5 N! Measurements of \ [ SI\ ] is a parsec is a convenient unit of is! Measure time, determine the approximate diameter of the material of the Scientific method ( in fact, you. As quasars ) have many puzzling features, which is used in chapters... Sphere is measured by a scale of least count 0.1 cm is 110.0 cm analysis an equation be! 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