273 + Interview Questions in PHYSICAL-WORLD-AND-MEASUREMENT IN GENERAL AWARENESS Page 4 InterviewSolution

151.	Find the number of significant figures in 0.005.
Answer» Correct Answer - one

Discussion

152.	Assertion : Number of significant figure in `0.005` is one and that is `0.500` is three Reason : This is became zeros are not significantA. Statement -1 is true, Statement -2 is true , and Statement -2 is correct explanation of Statement -1.B. Statement -1 is true , Statement -2 is true, but Statement -2 is not a correct explanation of Statement -1.C. Statement-1 is true, but Statement -2 is false.D. Statement-1 is false, but Statement -2 is true.
Answer» Correct Answer - (c ) In a number less then one, zero between the decimal point and first non zero digit are not significant. But zeros to the right of last non zero digit are significant. Statement-1 is true, but statement -2 is false.

Discussion

153.	How far away is the nearst star alpha centuri from earth ?
Answer» The distance of nearest star alpha centuri from earth is `~= 10^(16) metre.`

Discussion

154.	The diameter of a circle is 2.486 m. Calculate the area with due regard to significant figures.A. `4.85 m^3`B. `4.85454 m^3`C. `4.854 m^3`D. `4.8545 m^3`
Answer» Correct Answer - (c ) Here, `D = 2.486 m, pi = 3.142` As Area `=(pi D^2)/(4) = (3.142xx(2.486)^2)/(4)` `=(3.142xx6.180196)/(4) = (19.418175832)/(4)` `=4.85454m^3` Since, the diameter has been expressed in four significant figures, final result of area should also be expressed in four significant figures. `A = 4.854 m^3`

Discussion

155.	The diameter of circle is 1.06m. Calculate the area enclosed by the circle in correct number of significant figures.
Answer» Correct Answer - `0.882m^2` Here, D = 1.06m, A =? `A = (pi D^2)/(4) = (3.14)/(4)(1.06)^2 = 0.8820 m^2` Rounding offf to three significant figures `A = 0.882 m^2`

Discussion

156.	Inverse square law of distance is followed byA. gravitational forcesB. electromagnetic forcesC. both (a) and (b) aboveD. neither (a) not (b)
Answer» Correct Answer - (c )

Discussion

157.	Force of friction and tension in a string areA. gravitational forcesB. weak forcesC. electromagnetic forcesD. nuclear forces
Answer» Correct Answer - (c )

Discussion

158.	Which of the following in not the unit of surface tension ?A. `N//m`B. `J//m^2`C. `kg//s^2`D. none of these
Answer» Correct Answer - (d) Surface tension `= ("force")/("length") = (MLT^(-2))/(L) = [MT^(-2)]` :. Units of S.T. can be `N//m , J//m^2` and `kg //s^2` Choice (d) is correct.

Discussion

159.	Given that `y = a cos((t)/(P) - qx),` where t represents distance is metre. Which of the following statements is true ?A. unit of t is same as that of pB. unit of t is same as that of qC. unit of x is same as that of qD. unit of x is same as that of P
Answer» Correct Answer - (a) In the given equation `((t)/(p) - qx) = theta` = dimensionless. Therefore, unit of t must be same as that of p.

Discussion

160.	In terms of potential difference `C`, electric current`I` , permittivity `epsilon_(0)`, permeability `mu_(0)` and speed of light `c`, the dimensionally correct equation `(s)` is `(are)`A. `mu_0 I^2 = epsilon_0 V^2`B. `epsilon_0 I = mu_0 V`C. `I = epsilon_0 cV`D. `mu_0 cI = epsilon_0V`
Answer» Correct Answer - (a,c) Here, Dimnsional formula for `(i) V =ML^2 T^(-3) A^(-1)` `(ii) I= [A^1]` (iii) `c= [LT^(-1)]` (iv)`epsilon_0 = [M^(-1) L^(-3) T^4 A^2]` (v) `mu_0 =[M^1 L^1 T^(-2) A^(-2)]` (a) `mu_o I^2 =epsilon_0 V^2` `MLT^(-2) A^(-2)xxA^2 = M^(-1) L^(-3) T^4 A^2xx(ML^2 T^(-3) A^(-1))^2` `MLT^(-2) = MLT^(-2)` Hence option (a) is correct. (b) `epsilon_0I =mu_0V` `M^(-1)L^(-3) T^2 A^2xxA = M^1 L^1 T^(-2) A^(-2)xxML^2 T^(-3)A^(-1)` `M^2 L^3 T^(-5) A^(-3)` `:. LHS =! RHS, dimensionally.` Hence option (b) is incorrect. (c ) `I = epsilon_0 cV` `A = M^(-1) L^(-3) T^4 A^2 xx LT^(-1)xxML^2 T^(-3) A^(-1) = A` L.H.S. = R.H.S., dimensionally. Hence option (c ) is correct. (d) `mu_0 cI = epsilon_0 V` `M^1 L^1 T^(-2) A^(-2) xx LT^(-1) xxA` `=M^(-1) L^(-3) T^4A^2 xx ML^2 T^(-3) A^(-1)` `M^1 L^2 T^(-3)A^(-1) =! M^0 L^(-1) T^1 A^1` L.H.S =! R.H.S. Hence option (d) is incorrect.

Discussion

161.	What is meant by order of magnitude of a quantity ?
Answer» Order of magnitude of a quantity is defined as the power of 10, which gives us a value nearst to the actual value of the quantity.

Discussion

162.	What is the shortest distance measured indirectly so far ?
Answer» The sortest distance measured indirectly so far is radius of a proton`(~~10^(15)m).`

Discussion

163.	Explain the concept of mass, length and time. Why mass, length and time are called fundamental quantites.
Answer» 1 (b). 3, 1 (b). 4, 1 (b) 5 and 1 (b) .6

Discussion

164.	Justify `L + L = L`and `L-L =L`
Answer» when distance is added to distance, we get distance only. This justifies L +L =L Again, when distance is subtracted from distance, we again obtain some distance. This Justifies L -L =L.

Discussion

165.	A U - tube of uniform cross section contains mercury upto a height h in either limb. The mercury in one limbe is depressed a little and then relased. Obtain an expression for time period (T) of oscillation, assuming that T depends on h,`rho` and g, where `rho` is density of mercury.
Answer» Correct Answer - `T =Ksqrt((h)/(g))` Let `T = Kh^a rho^b g^c` where a,b,c are the dimensions and k is dimensionless constant. Writing the dimensions in (i) we get `[M^0L^0T^1] = L^a(ML^(-3))^b (LT^(-2))^c` `=M^b L^(a -3b +c T^(-2c)` Applying the principle of homogeneity of dimensions, we get `b= 0, a-3b +c =0, -2c =1, c = (1)/(2).` From `a-3b + c =0, a-3xx0 - (1)/(2) =0, a =(1)/(2)`1 Putting these value in (i) we get `T = K h^(1//2) rho^0 g^(-1//2)` `T = K(sqrth/sqrtg)`

Discussion

166.	Name two Indian physicists who have won Noble Prize in Physics.
Answer» Sir C.V Raman and S. Chandrashekhar.

Discussion

167.	who maintains indian Standard Time ?
Answer» The indian Standerd Time (IST) is maintained by the National Physical Laboratory (NPL) in New Delhi , using a cesium atoic clock.

Discussion

168.	What is the advantage in choosing the wavelength of light readination as a standard of length?
Answer» The fundamental unit of length, i.e., metre has been defined in terms of wavelengths because : (i) wavelength is accurately defined, (ii) it is not affected by changes in place, time and physical conditions like temperature, (iii) it is easily reproducible in any good laboratory.

Discussion

169.	In difining the standerd of length, we have to specify the temperature at which the measurement should be made. Are we justified in calling length a fundamental quantity, if another physical quantity (temperature) has to be specified in choosing a standeard?
Answer» The length of an object changes with temperature but the unit for measuring length (i.e., metre) has now been defined in terms of wavelength of light. This is not affected by temperature. Hence, the choice of length as a fundamental units is justified.

Discussion

170.	what is the scientific principle of calculators and computers ?
Answer» Digital logic of electronic circuits is the underlying principle of calculators and computers.

Discussion

171.	The dimensionas of universal gravitational constant are ____A. `[M^1 L^3 T^(-2)]`B. `[M^1 L^(-3) T^2]`C. `[M^(-1) L^3 T^(-2)]`D. `[M^(-1) L^3 T^2]`
Answer» Correct Answer - (c )

Discussion

172.	Which of the following is not a dimensional variable ?A. densityB. specific gravityC. angleD. strain
Answer» Correct Answer - (a)

Discussion

173.	Time taken by light to cross nuclear diameter is of the order ofA. `10^(22)s`B. `10^(-6)s`C. `10^(-14)s`D. `10^(-22)s`
Answer» Correct Answer - (d)

Discussion

174.	Generation, propagation and detection of electromagnetic waves is the basis ofA. ComputersB. ReactorsC. Radio and TelevisionD. Lasers
Answer» Correct Answer - (c )

Discussion

175.	Optical fibers are based onA. total internal reflectionB. refractionC. dispersionD. none of these
Answer» Correct Answer - (a)

Discussion

176.	Which of the following is a dimensional variable ?A. forceB. exponential eC. angleD. velocity of light in vacuum
Answer» Correct Answer - (a)

Discussion

177.	Who discovered X-rays ?
Answer» Correct Answer - Roentgen.

Discussion

178.	What is electromagnetic force?
Answer» It is force due to interaction between two moving charges. This force is caused by the exchange of photons between the two charged particles.

Discussion

179.	Astrology is a science. Comment.
Answer» A strology predicts events on the basis of positions of different planets at different times. For example, it predicts the same fate for all children born at the same time. This is not found to be true. An astrologer makes many predictions, some of which may turn out to be ture and others false. As astrology is not based on scientific laws, we cannot call it a science.

Discussion

180.	How many times is a millisecond larger then a microsecond ?
Answer» `10^3 times :. (1 millisec)/(1 microsec) = (10^(-3)s)/(10^(-6)s) = 10^3`

Discussion

181.	If the unit of force ware kilonewton, that of time millisecond and that of power kilowatt, what would be the units of mass and length?
Answer» Correct Answer - `1kg ; 10^(-3)` Here,`F = M^1 L^1 T^(-2) =1kN = 1000N …..(i)` `T = T^1 = 1 ms = 10^(-3)s …(ii)` `P = ML^2 T^(-3) =1 kW = 1000W …….(iii)` `(F)/(T) = M^1 L^1 T^(-3) = (1000)/(10^(-3)) = 10^6 Ns^(-1) ….(iv)` Divide (iii) by (iv) `(ML^2T^(-3))/(MLT^(-3)) = (1000)/(10^6) = 10^(-3) or L = 10^(-3)m` Put values of L & T in (i) `M(10^(-3))(10^(-3))^(-2) = 10^3` :. M =1kg

Discussion

182.	In the expression `P =E I^2 m^(-5) G^9(-2),` E, m, I and G denote energy, mass, angular momentum and gravitational constant, respectively. Show that P is a dimensionless quantity.
Answer» Here, ` P = E I^2 m^(-5) G^(-2) = [ML^2 T^(-2)] [ML^2 T^(-1)]^2[M]^(-5) [M^(-1) L^3 T^(-2)]^(-2) = M^(1 + 2 -5 +2) L^(2 + 4-6) T^(-2-2 +4)` `P = [M^0 L^0 T^0]` Hence , P is a dimensionless quantity.

Discussion

183.	If h is the height or depth (sagitta) of a spherical surfacce and I is the mean distance between the legs of sphermoeter, then radius of curvature R of the surface isA. `R =(I^2)/(h) + (h)/(2)`B. `R = (I^2)/(6h) + (h)/(2)`C. `R =(I^2)/(6h) - (h)/(2)`D. `R = (h^2)/(6I) + (I)/(2)`
Answer» Correct Answer - (b) The correct relation for R is `R = (I^2)/(6h) + (h)/(2)`

Discussion

184.	In the above question, what is the difference in lengths of the two pieses of wire ?
Answer» Correct Answer - `(12.2 +- 0.3) cm` Here, `I_1 =(35.2+- 0.1)cm` `I_2 =(47.4+- 0.2)cm` `I_2 -I_1 =47.4 -35.2 =12.2 cm` Error in difference of lengths `=+-(0.1+0.2)cm` `= +- 0.3cm` `I_1 - I_2 =(12.2 +- 0.3)cm`

Discussion

185.	Fundamental forces in nature have been classified as : Gravitational forces, weak forces, electromagnetic forces and nuclaer forces. Gravitational forces are weakest of all forces and nuclear forces are the stronges of all. Whereas gravitational forces operate over very long distance, the nuclear forces are confined only within the nucleus. Read the above passage and answer the following questions : (i) Which forces are central forces ? (ii) Which forces are non conservative forces ? (iii) What value of life do you learn from this study ?
Answer» (i) Gravitational foces and electromagnetic forces are central forces. (ii) Weak forces and nuclear forces are non conservative forces. (iii) We find that gravitational forces which are weakest have the longest range, and nuclear forces, which area strongest, have the shortest range. in day to day life, it implies that when you spend energy at a slow rate `(i.e., (dU)/(dr) = F ="small")`, you last longer `(i.e., "range is longer")`. And when you spend energy at a much faster rate `(i.e., (dU)/(dt) = F = "large")`, you become extinct much sooner `("i.e., over a short distance")`. it also implies that slow and steady wins the race.

Discussion

186.	If the value of universal gravitational constant is `6.67xx10^(11) Nm^2 kg^(-2),` then find its value in CGS system.
Answer» Correct Answer - `6.67xx10^(-8) dyne cm^2 g^(-2)` The dimensinal formula of G is `[M^(-1)L^3 T^(-2)]` To convert MKS system to CGS system, we write `M_1 = 1kg, L_1 =1m, T_1 =1s,` `n_1 = 6.67xx10^(-11)` `M_2 =1g, L_2 = 1cm, T_2 =1s, n_2 =?` `n_2 =n_1((M_1)/(ML_2))^(-1) ((L_1)/(L_2))^3((T_1)/(T_2))^(-2)` `=6.67xx10^(11)((1kg)/(1g))^(1) ((1m)/(1cm))^3 ((1s)/(1s))^(-2)` `=6.67xx10^(-11)xx(10^3)^(-1)xx(10^2)^3xx1` `=6.67xx10^(-8) dyne cm^2g^(-2)`

Discussion

187.	when `y =s^4,` what is the relative error in y?
Answer» `(Deltay)/(y) = 4((Deltax)/(x))`, i.e., it is four times the relative error in x.

Discussion

188.	A physcial quantity `x =a^2 b^(-3//2)/(c^4)` has a relative error `(Deltax)/(x) =2(Deltaa)/(a) - (3)/(2) (Deltab)/(b) -4(Deltac)/(c )` .is the statement correct?
Answer» No, as combined error is additive only without algebraic sign. The correct statement is `(Deltax)/(x) = 2(Deltaa)/(a) +(3)/(2) (Deltab)/(b) +4(Delta)/(c )`

Discussion

189.	fill in the blanks by suitable conversion of units : (i) `5ms^(-2) = ……. Km h^(-2)` (ii) `G = 6.67 xx 10^(-11) Nm^2 kg^(-2)` `=….. Cm^3 s^(-2) g^(-1)`
Answer» Correct Answer - `6.480xx10^4 km h^(-2)` ;` 6.67 xx10^(-8) cm^3 s^(-2) g^(-1)` (i) `5ms^(-2) =5 (10^(-3)km) ((1)/(60xx60)h)^(-2)` `=5xx10^(-3)xx3600xx3600 km h^(-2)` `=6.480 xx 10^4 km h^(-2)` (ii) `G = 6.67xx10^(11)Nm^2 kg^(-2)` `=6.67xx10^(-11)(kgms^(-2)) m^2 kg^(-2)` `= 6.67 xx10^(-11) m^3 s^(-2) kg^(-1)` `=6.67 x10^(-11) (10^2 mc)^3(10^3 g)^(-1)` `G = 6.67x10^(-8) cm^3 s^(-2) g^(-1)`

Discussion

190.	The relative density of lead is 11.3. its density `= ….. g cm^(-3) = …….kg m^(-3)`. Fill in the blanks.
Answer» Correct Answer - `11.3 g cm^(-3) = 11.3xx10^3 kg m^(-3)` Density = Relative density xx density of water `=11.3g cm^(-3)xx1g cm^(-3) = 11.3g cm^3` `11.3xx10^3kg m^(-3)`

Discussion

191.	State three important conservation laws used in Classical Physics.
Answer» Correct Answer - 1 (a) 11

Discussion

192.	Let `[in_(0)]` denote the dimensional formula of the permittivity of vacuum. If `M = mass, L = length, T = time and A = elctric current`, then :A. `[In_0]= [M^(-1) l^(-3) T^2 I]`B. `[in_0] = [M^(-1) L^(-3) T^4 I^2]`C. `[mu_0] = [MLT^(-2) I^(-2)]`D. `[mu_0] = [ML^2 T^(-2)I]`
Answer» Correct Answer - (b,c) As `F = (1)/(4 pi in_0) (q^2)/(r^2) or in_0 = (1)/(4pi) (q^2)/(r^2 F)` `epsilon_0 = (I^2 T^2)/(L^2 MLT^(-2)) = M^(-1) L^(-3)T^4 I^2` As `B = (mu_0)/(4 pi) (I dl sin theta)/(r^2)` `(F)/(qupsilon) =(mu_0)/(4pi) xx (I din sin theta)/(r^2) [ :. F =B q upsilon sin theta]` `mu_0 =(Fr^2)/(q upsilon dl) = (MLT^(-2).L^2)/(IT.LT^(-1). I.L) = MLT^(-2) I^(-2)` Choices (b) and (c ) are correct.

Discussion

193.	Identify the physical quantity x defined as `x = (I F upsilon^2)/(W I^3),` where I is moment of inertia, F is force, `upsilon` is veloicty, W is work and I is length.
Answer» As is known, `I = ML^2 , F= MLT^(-2), upsilon = LT^(-1)` `W = ML^2 T^(-2),l = L` `:. X =(Ifupsilon^3)/(WI^3) = ((ML^(2))(MLT^(-2))(LT^(-1))^(2))/((M^(1)L^(0)T^(-2))L^(3))` `= [M^1 L^0 T^(-2)]` These are the dimensions of surface tension or force constant or energy per unit area.

Discussion

194.	which of the following measurements is most precise ?A. 5.00 mm,B. 5.00 cmC. 5.00 mD. 5.00 km
Answer» Correct Answer - (a) All measurements are correct upto two places of decimal. However, the absolute error in (a) is 0.01 mm, which is least of all the four. So, it is most precise.

Discussion

195.	Precise measurements of phsysical quantites area need of science. For example, to accertain the speed of an aircraft, one must have an accurte method to find its positions at clsely separted instants of time. This was the actual motivation behind the discovery of radar in World War II. Think of different examples in modern science where precise measurements of length, time mass etc. are needed. Also, wherever you can, give a quantitative idea of the precision needed.
Answer» Preciese measurements of physcial quantites like length, mass and time are the primary requirements fro development fo quatitative laws of Physics or any other science. For example in the measurement of distance of moon form earth by Laser beam, very accurate measurement of time taken is required. Similoarly, for measuring distance, elevation and velocity of an aeroplane by Radar method, time measruement has to be accurate. For measurig distance of nearby stars, accurate measurement of parallax angle is required. in the field of crystallography, precise measurement of lenght is needed to determine interatomic distaances. Using a mass spectrometer. the precision measurement of masses of atoms are made.

Discussion

196.	Which of the following are not a unit of time ?A. secondB. ParsecC. YearD. Light year
Answer» Correct Answer - (b,d) Parsec and light year, both are units of distance , and not of time.

Discussion

197.	Calculate the dimensions of impulse in terms of velocity `(upsilon)` denity `(rho)` and frequeny (v) as fundamental units.
Answer» Let impulse, `I = k upsilon^a rho^b v^c …..(i)` where a, b,c are the dimensions and k is dimen- sionless constant. Writing the dimensions, `[MLT^(-1)] = (LT^(-1))^a (ML^(-3))^b (T^(-1))^c` `= M^b L^(a-3b) T^(-a-c)` Applying the principle of homogeneity of dimensios, we get b=1, `a- 3b =1, a = +3b+ 1 =+3 +1 = +4` `-a - c =-1, c= -a +1 = -4+1 = -3` Putting these values in (i) we get `I = k upsilon^4 rho^1 v^(-3) = k(rho upsilon^4)/(v^3)`

Discussion

198.	If the fundamental quantites are velocity `(upsilon)`, mass (M), time (T), what will be the dimensions of `eta` in the equaiton `V = (pi pr^4)/(8I eta)` where the symbosl have their usual meaning?
Answer» Correct Answer - `M^1 upsilon^(-1) T^(-2)` From `V =(pi)/(8) (pr^4)/(I eta)` `eta =(pi)/(8)(pr^4)/(IV) where V = volume//sec = [L^3 T^(-1)]` `eta = ([ML^(-1)T^(-2)][L^4])/(L[L^3 T^(-1)]) = [M^1L^(-1) T^(-1)]` As `upsilon =("dinstance")/("time") =(L)/(T) , L =upsilon T` `:.eta =ML^1 (upsilonT^(-1))T^(-1) =[M^1 upsilon^(-1) T^(-2)]`

Discussion

199.	If random error in the arithmetic mean of 100 observations is x, then the randow error in the arithmetic mean of 500 observations would beA. 5xB. `x//5`C. 25xD. `x//25`
Answer» Correct Answer - (b)

Discussion

200.	In the division of two quantities, the maximum value of fractional error is equal toA. difference of fractional errors in the individual quantitiesB. sum of fractional errors in the individual quantitiesC. Either (a) or (b)D. Neither (a) not (b)
Answer» Correct Answer - (b)

Discussion

Explore topic-wise InterviewSolutions in .

Find the number of significant figures in 0.005.

How far away is the nearst star alpha centuri from earth ?

The diameter of a circle is 2.486 m. Calculate the area with due regard to significant figures.A. `4.85 m^3`B. `4.85454 m^3`C. `4.854 m^3`D. `4.8545 m^3`

The diameter of circle is 1.06m. Calculate the area enclosed by the circle in correct number of significant figures.

Inverse square law of distance is followed byA. gravitational forcesB. electromagnetic forcesC. both (a) and (b) aboveD. neither (a) not (b)

Force of friction and tension in a string areA. gravitational forcesB. weak forcesC. electromagnetic forcesD. nuclear forces

Which of the following in not the unit of surface tension ?A. `N//m`B. `J//m^2`C. `kg//s^2`D. none of these

Given that `y = a cos((t)/(P) - qx),` where t represents distance is metre. Which of the following statements is true ?A. unit of t is same as that of pB. unit of t is same as that of qC. unit of x is same as that of qD. unit of x is same as that of P

In terms of potential difference `C`, electric current`I` , permittivity `epsilon_(0)`, permeability `mu_(0)` and speed of light `c`, the dimensionally correct equation `(s)` is `(are)`A. `mu_0 I^2 = epsilon_0 V^2`B. `epsilon_0 I = mu_0 V`C. `I = epsilon_0 cV`D. `mu_0 cI = epsilon_0V`

What is meant by order of magnitude of a quantity ?

What is the shortest distance measured indirectly so far ?

Explain the concept of mass, length and time. Why mass, length and time are called fundamental quantites.

Justify `L + L = L`and `L-L =L`

A U - tube of uniform cross section contains mercury upto a height h in either limb. The mercury in one limbe is depressed a little and then relased. Obtain an expression for time period (T) of oscillation, assuming that T depends on h,`rho` and g, where `rho` is density of mercury.

Name two Indian physicists who have won Noble Prize in Physics.

who maintains indian Standard Time ?

What is the advantage in choosing the wavelength of light readination as a standard of length?

In difining the standerd of length, we have to specify the temperature at which the measurement should be made. Are we justified in calling length a fundamental quantity, if another physical quantity (temperature) has to be specified in choosing a standeard?

what is the scientific principle of calculators and computers ?

The dimensionas of universal gravitational constant are ____A. `[M^1 L^3 T^(-2)]`B. `[M^1 L^(-3) T^2]`C. `[M^(-1) L^3 T^(-2)]`D. `[M^(-1) L^3 T^2]`

Which of the following is not a dimensional variable ?A. densityB. specific gravityC. angleD. strain

Time taken by light to cross nuclear diameter is of the order ofA. `10^(22)s`B. `10^(-6)s`C. `10^(-14)s`D. `10^(-22)s`

Generation, propagation and detection of electromagnetic waves is the basis ofA. ComputersB. ReactorsC. Radio and TelevisionD. Lasers

Optical fibers are based onA. total internal reflectionB. refractionC. dispersionD. none of these

Which of the following is a dimensional variable ?A. forceB. exponential eC. angleD. velocity of light in vacuum

Who discovered X-rays ?

What is electromagnetic force?

Astrology is a science. Comment.

How many times is a millisecond larger then a microsecond ?

If the unit of force ware kilonewton, that of time millisecond and that of power kilowatt, what would be the units of mass and length?

In the expression `P =E I^2 m^(-5) G^9(-2),` E, m, I and G denote energy, mass, angular momentum and gravitational constant, respectively. Show that P is a dimensionless quantity.

If h is the height or depth (sagitta) of a spherical surfacce and I is the mean distance between the legs of sphermoeter, then radius of curvature R of the surface isA. `R =(I^2)/(h) + (h)/(2)`B. `R = (I^2)/(6h) + (h)/(2)`C. `R =(I^2)/(6h) - (h)/(2)`D. `R = (h^2)/(6I) + (I)/(2)`

In the above question, what is the difference in lengths of the two pieses of wire ?

If the value of universal gravitational constant is `6.67xx10^(11) Nm^2 kg^(-2),` then find its value in CGS system.

when `y =s^4,` what is the relative error in y?

A physcial quantity `x =a^2 b^(-3//2)/(c^4)` has a relative error `(Deltax)/(x) =2(Deltaa)/(a) - (3)/(2) (Deltab)/(b) -4(Deltac)/(c )` .is the statement correct?

fill in the blanks by suitable conversion of units : (i) `5ms^(-2) = ……. Km h^(-2)` (ii) `G = 6.67 xx 10^(-11) Nm^2 kg^(-2)` `=….. Cm^3 s^(-2) g^(-1)`

The relative density of lead is 11.3. its density `= ….. g cm^(-3) = …….kg m^(-3)`. Fill in the blanks.

State three important conservation laws used in Classical Physics.

Let `[in_(0)]` denote the dimensional formula of the permittivity of vacuum. If `M = mass, L = length, T = time and A = elctric current`, then :A. `[In_0]= [M^(-1) l^(-3) T^2 I]`B. `[in_0] = [M^(-1) L^(-3) T^4 I^2]`C. `[mu_0] = [MLT^(-2) I^(-2)]`D. `[mu_0] = [ML^2 T^(-2)I]`

Identify the physical quantity x defined as `x = (I F upsilon^2)/(W I^3),` where I is moment of inertia, F is force, `upsilon` is veloicty, W is work and I is length.

which of the following measurements is most precise ?A. 5.00 mm,B. 5.00 cmC. 5.00 mD. 5.00 km

Which of the following are not a unit of time ?A. secondB. ParsecC. YearD. Light year

Calculate the dimensions of impulse in terms of velocity `(upsilon)` denity `(rho)` and frequeny (v) as fundamental units.

If the fundamental quantites are velocity `(upsilon)`, mass (M), time (T), what will be the dimensions of `eta` in the equaiton `V = (pi pr^4)/(8I eta)` where the symbosl have their usual meaning?

If random error in the arithmetic mean of 100 observations is x, then the randow error in the arithmetic mean of 500 observations would beA. 5xB. `x//5`C. 25xD. `x//25`

In the division of two quantities, the maximum value of fractional error is equal toA. difference of fractional errors in the individual quantitiesB. sum of fractional errors in the individual quantitiesC. Either (a) or (b)D. Neither (a) not (b)