NEET Physics units and measurements Test-7 July 16, 2017admin0 Comments CategoriesNEET Foundation Class-VIII NEET Physics units and measurements Test-7 1. The liquid drop of density ρ, radius r and surface tension a oscillates with time period T. Which of the following expression for T^{2} is correct. ρr^{3}/&;sigma ρ σ /r^{3} r^{3}σ /ρ None 2. The volume of a liquid (v) flowing per second through a cylindrical tube depends upon the pressure gradient (p/l) radius of the tube (r) coefficient of viscosity (η) of the liquid by dimensional method the correct formula is V ∝ [(Pr^{4})/( ηl)] V ∝ [(Pr)/ (ηl^{4})] V ∝ [(Pl^{4})/ (ηr)] none 3. The dimensions of resistivity in terms of M, L, T and Q, where Q stands for the dimensions of charge is ML^{3}T^{-1}Q^{–}2 ML^{3}T^{-2}Q^{-1 } ML^{2}T^{-1}Q^{-1} MLT^{-1}Q^{-1} 4. The distance travelled by a particle in n^{th} second is S^{n} = u + $latex frac { a }{ 2 } (2n – 1) $ where u is the velocity and a is the acceleration. The equation is dimensionally true dimensionally false numerically may be true or false 1 and 3 are correct 5. The position of a particle at time ‘t’ is given by the equation : x(t) = $latex frac { V_{0} }{A } (1 – e^{At}) $; V_{0}= constant and A > dimensions of V_{0} and A respectively are ; M^{0}LT^{° }and T^{-1} M^{0}LT^{-1} and LT^{-2 } M^{0}LT^{-1} and T M^{0}LT-1 and T^{-1} 6. If J is the angular momentum and E is the kinetic energy, then J^{2}/E has the dimensions Moment of Inertia Power Angular velocity Impulse 7. If L is the inductance, C is the capacitance and R is the resistance, then $latex R sqrt { frac { C }{ L } } $ has the dimension MLT^{ -2} I^{ -2} ML^{ 2} T^{ 2} I ML^{ -1} T^{ -2}^{ I-1 } M^{ 0} L^{ 0} T^{ 0} I^{ 0} 8. If h is Planck’s constant and, &lamda;is the wavelength, h/&lamda; has the dimensions of Energy Momentum Moment of Inertia Frequency 9. The power of a motor is 200W. If the unit of length is halved, that of mass is doubled and that of time is Ac doubled, then the power of the motor in the new system is 3200 W 3200 new units 12.5 new units 12.5 W 10. If the unit of mass is α kg, the unit of length is β metre and the unit of time is ‘ γ ‘ second, The magnitude of calorie in the new system is (1 Cal = 4.2 J) 4.2α ^{2} β^{2} γ ^{2 }new units 4.2 α^{-1 }β ^{-2 }γ ^{2} new units α^{ -1 }β^{ -2} γ ^{2} new units (1/4.2) α ^{-1 }β^{ -2} γ ^{2 }new units 11. If the mass of the electron (9x 10^{-31}kg) is taken as unit of mass, the radius of the first Bohr orbit 0.5×10^{-10}m) as unit of length and 500 newton as the unit of force, then the unit of time in the new system would be 3×10^{-22}s 15 x 10^{-12}s 15 x 10^{-20}s 45 x 10^{-20}s 12. If pressure P, velocity of light C and acceleration due to gravity g are chosen as fundamental units, then dimensional formula of mass is PC^{3}g^{-4} PC^{-4}g^{3} PC^{4}g^{-3 } PC^{4}g^{3} 13. If young’s modulus y, surface tension s and time t are the fundamental quantities then the dimensional formula of density is s^{2}s^{3}t^{-2} s^{3}y^{3}T^{-2 } s^{-2}y^{3}T^{2 } s^{-2} y^{2}T^{3} 14. If P represents radiation pressure, C speed of light, and Q radiation energy striking unit area per second and x,y,z are non zero integers, then P^{x }Q^{y} C^{z} is dimensionless. The values of x,y and z are respective 1,1,-1 1,-1,1 -1,1,1 1,1,1 15. If the time period (T) of vibration and liquid drop depends on surface tension (S), radius (r) of the drop and density (ρ) of the liquid, then the expression of T is $latex T=Kfrac { sqrt { { & rho; }{ r }^{ 3 } } }{ { S }^{ 2 } } $ $latex T=Kfrac { sqrt { { & rho; }^{ 1/2 }{ r }^{ 3 } } }{ { S } } $ $latex T=Kfrac { sqrt { { & rho; }{ r }^{ 3 } } }{ { S }^{ 1/2 } } $ $latex T=Kfrac { sqrt { { & rho; }^{1/ 2 }{ r }^{ 3 } } }{ { S } } $ 16. Suppose, the torque acting on a body is given by T=KL+xI/(ω) . Where L = angular- momentum, I= moment of inertia, omega= angular speed. The dimensional formula for Kx is same as that for time^{2} time^{4} time^{-2} time^{-4} 17. The number of particles crossing unit area perpendicular to x-axis in unit time is given by n=-[-D(n_{2}-n_{1})]/[x_{2}-x_{1}]where n_{1} and n_{2} are number of particles per unit volume for the value of x meant to x_{1}and x_{2}. The dimensions of D are M^{0}L T^{3} M^{0}L^{2}T^{-2} M^{0}L T^{-2} M^{0}L^{2} T^{-1} 18. Turpentine oil is flowing through a capillary tube of length 1 and radius r. The pressure difference between the two ends of the tube is P. The viscosity of oil is given by : η=[P(r^{2}-x^{2})]/[4vl]fd. Here v is velocity of oil at a distance x from the axis of the tube. From this relation, the dimensional formula of η is ( ML^{-1}T^{-1}) [MLT^{-1}] [ML^{2}T^{-2}] [M^{0}L^{0}T^{0}] 19. Dimensional formula of the product of the two physical quantities P and Q is ML^{2}T^{-2}, the dimension formula of (P/Q) is MT^{ -2}. P and Q respectively are Force, velocity Momentum, displacement Force, displacement Work, velocity 20. The potential energy of a particle varies with distance x from a fixed origin as $latex V = frac { Asqrt { x } }{ x+B } $ where A and B are constants. The dimensions of AB are M^{1}L^{5/2}T^{=2} M^{1}L^{2}T^{=2 } M^{3/2}L^{5/2} T^{-2} M^{1}L^{7/2}T^{-2} 21. If h is the Planck’s constant, m = mass of die electron, e – charge of the electron and ε_{0 }= permittivity of vacuum, then [(h^{2}ε_{0})/(me^{2})] has the unit newton joule 3} watt metre 22. ii the displacement y of a particle is y = A sin(pt + qx), then dimensional formula of ‘ Apq ‘ is L LT^{-1 } T^{-1 } L^{-1} T^{-1} 23. A circular railway track of radius r is banked at angle θ so that a train moving with speed u can safely go round the track. A student writes : tan θ = rg/v^{2} Why this relation is not correct ? Equality of dimensions does not guarantee correctness of the relation. Dimensionally correct relation may not be numerically correct. The relation is dimensionally incorrect. i)&(ii) (ii)&(iii) (iii)&(i) (i), (ii) & (iii) 24. The parameter $latex frac { m{ Q }^{ 4 } }{ { { varepsilon }_{ 0 } }^{ 2 }{ h }^{ 2 } } $ has the dimensions of (m = mass, Q = charge, epesolonat _{0} Permittivity and h = Planck’s constant) Wavelength Power Angular momentum Energy 25. The dimensional formula of( 1/2) ε_{0} E^{2} is(ε_{0} is permittivity of free space and E is electric field) ML^{2}T^{-2} MLT^{-2} ML^{-1}T^{-2} ML ^{-2}T^{-1} Loading … Related posts: NEET Physics units and measurements Test-3 NEET Physics units and measurements Test-4 NEET Physics units and measurements Test-5 NEET Physics units and measurements Test-6 NEET Physics units and measurements Test-8 Powered by YARPP.