Tiêu đề PHYSICAL WORLD, UNITS & DIMENSION.pdf ✅

Physical World, Units and Dimension & Errors in Measurement  Digital www.allendigital.in [ 99 ] UNIT 1. Which of the following system of units is not based on units of mass, length and time alone ? (1) SI (2) MKS (3) FPS (4) CGS 2. Which of the following is not a fundamental physical quantity ? (1) Mass (2) Length (3) Temperature (4) Density 3. Which of the following is not the name of a physical quantity :- (1) kilogram (2) impulse (3) energy (4) density 4. Which of the following is not a unit of time ? (1) microsecond (2) leap year (3) lunar month (4) light year 5. Unit of energy in SI system is :- (1) erg (2) calorie (3) joule (4) electron volt 6. In the SI system, the unit of temperature is :- (1) Degree centrigrade (2) Degree Celsius (3) Kelvin (4) Degree Fahrenheit 7. The SI unit of momentum is :- (1) kg m (2) kg.m sec (3) 2 kg.m sec (4) kg × newton 8. SI unit of pressure is :- (1) pascal (2) Dyne/cm2 (3) cm of Hg (4) atmosphere 9. kg m/s2 stand for the unit of :- (1) Energy (2) acceleration (3) Force (4) Momentum 10. N kg–1 is the unit of :- (1) velocity (2) energy (3) acceleration (4) force 11. If the unit of length is micrometre and unit of time is microsecond, the unit of velocity will be :- (1) 100 m/s (2) 10 m/s (3) micrometre/s (4) m/s 12. The unit of power is :- (1) kilowatt (2) kilowatt-hour (3) dyne (4) joule 13. Kilowatt-hour is a unit of :- (1) electrical charge (2) energy (3) power (4) force 14. One nanometer is equal to :- (1) 109 mm (2) 10–6 cm (3) 10–7 cm (4) 10–9 cm 15. The units nanometre, fermi, angstrom and attometre, arranged in decreasing order will read as :- (1) angstrom, nanometre, fermi, attometre (2) fermi, attometre, angstrom, nanometre (3) nanometre, angstrom, fermi, attometre (4) attometre, angstrom, fermi, nanometer 16. Which is the correct unit for measuring nuclear radii:- (1) micron (2) millimetre (3) agnstrom (4) fermi 17. Which of the following is usually a derived quantity? (1) Mass (2) Velocity (3) Length (4) Time 18. Temperature can be expressed as a derived quantity in terms of which of the following ? (1) Length and mass (2) Mass and time (3) Length. mass and time (4) None of these 19. Which of the following sets can not enter into the list of fundamental quantities in any system of units? (1) length, mass, velocity (2) length, time, velocity (3) length, time, mass (4) mass, time, velocity 20. The density of a liquid is 1000 kg m–3. Its value in CGS system :- (1) 1 gcm–3 (2) 0.1 gcm–3 (3) 10 gcm–3 (4) 100 gcm–3 21. The surface tension of a liquid is 70 dynes/cm. It may be expressed in M.K.S. system as :- (1) 70 N/m (2) 7 × 10–2 N/m (3) 7 × 102 N/m (4) 7 × 103 N/m Exercise - I
NEET : Physics [ 100 ] www.allendigital.in  Digital 22. Units of length, velocity and force are doubled. Which of the following is correct :- (1) Units of time is doubled (2) Unit of mass is doubled (3) Unit of momentum is doubled (4) Unit of energy is doubled 23. If the units of length, velocity and force are half, then the units of Power will be :- (1) doubled (2) halved (3) one fourth (4) remains unaffected DIMENSIONS 24. A dimensionless quantity (1) Never has a unit (2) Always has a unit (3) May have a unit (4) Does not exist 25. A unitless quantity (1) Does not exist (2) Always has a nonzero dimension (3) Never has a nonzero dimension (4) May have a nonzero dimension 26. Which of the following physical quantities has neither dimensions nor unit ? (1) angle (2) Luminous intensity (3) coefficient of friction (4) Electric current 27. Dimensions of relative density is (1) kg m–3 (2) [ML–3] (3) dimensionless (4) [M2 L–6] 28. Which of the following does not have dimensions of length ? (1) fermi (2) micron (3) angstrom (4) radian 29. The quantity having dimension –2 in the time is :- (1) force (2) pressure (3) gravitational constant (4) all of these 30. The dimensional formula [ML2T–2] represents :- (1) pressure (2) linear momentum (3) power (4) energy 31. Which pair has the same dimensions ? (1) Work and power (2) Density and relative density (3) Momentum and impulse (4) Latent heat and specific heat 32. Dimensions of one pair is same. Identify the pair:- (1) Torque and energy (2) Angular momentum and work (3) Energy and pressure (4) Light year and solar day 33. The method of dimensional analysis can be used to derive which of the following relations ? (1) N0e–t (2) A sin(t + kx) (3) 1 2 mv2 + 1 2 I2 (4) None of the above 34. If dimensions of A and B are different, then which of the following operation is valid ? (1) A B (2) e–A/B (3) A – B (4) A + B 35. Which of the following is incorrect statement (1) A dimensionally correct equation may be correct (2) A dimensionally correct equation may be incorrect (3) A dimensionally incorrect equation may be correct (4) A dimensionally incorrect equation is incorrect 36. Which of the following is incorrect ? (1) All derived quantities may be represented dimensionally in terms of the base quantities (2) A base quantity cannot be represented dimensionally in terms of other base quantities (3) The dimension of a derived quantity is never zero in any base quantity (4) The dimension of a base quantity in other base quantities is always zero. 37. If x = at + bt2, where x is in metre and t is in hour(hr), then unit of b will be :- (1) m2/hr (2) m (3) m/hr (4) m/hr2
Physical World, Units and Dimension & Errors in Measurement  Digital www.allendigital.in [ 101 ] 38. A force is given by F = at + bt2, where t is time. The dimensions of a and b are (1) [M L T–3] and [M L T–4] (2) [M L T–4] and [M L T–3] (3) [M L T–1] and [M L T–2] (4) [M L T–2] and [M L T0] 39. If S = 1 3 ft3, 'f' has the dimensions of - (S = distance, t = time) (1) [M0L–1T3] (2) [M1L1T–3] (3) [M0L1T–3] (4) [M0L–1T–3] 40. The time dependence of a physical quantity P is given by P = P0 exp(– t 2), where  is a constant and t is time. The constant  (1) is dimensionless (2) has dimensions [T–2] (3) has dimensions of P (4) has dimensions [T2] 41. Given the force F = Pt–1 + Qt. Here t is time. The unit of P is same as that of :- (1) displacement (2) velocity (3) acceleration (4) momentum 42. The force F, on a sphere of radius 'a' moving in a medium with velocity v is given by F = 6av. The dimensions of  are :- (1) [ ML–1T–1 ] (2) [ MT–1 ] (3) [ MLT–2 ] (4) [ ML–3 ] 43. The force is given in terms of time (t) and displacement (x) by the equation : F = A cos Bx + C sin Dt Then, the dimensions of D B are :- (1) MoLoTo (2) MoLoT–1 (3) MoL–1To (4) MoLT–1 44. For a body moving along x-axis, the distance travelled by body from a reference point is given as function of time t as x = at2 + b, where a and b are constants, then the dimension of ab is same as :- (1) speed (2) distance travelled (3) acceleration (4) none of these 45. In the relation y = r sin (t – kx) the dimensions of k  are :- (1) [M0L1T0] (2) [M0L1T–1] (3) [M0L0T3] (4) [M0L1T0] 46. A wave is represented by y = a sin (At – Bx + C) where A, B, C are constants. The dimensions of A, B, C are (1) T–1, L, M0L0L0 (2) T–1, L–1, M0L0L0 (3) T, L, M (4) T–1, L–1, M–1 47. For 10(at+3), the dimensions of a is :- (1) M0L0T0 (2) M0L0T1 (3) M0L0T–1 (4) None of these 48. The equation dv dt = AT – Bv is describing the rate of change of velocity of a body falling from rest in a resisting medium. The dimensions of A and B are :- (1) LT–3, T (2) LT–3, T–1 (3) LT, T (4) LT, T–1 49. If y represents distance and x-represents time, dimensions of 2 2 dy dx are :- (1) LT–1 (2) L2T2 (3) L2T–1 (4) LT–2 50. If energy (E), velocity (v) and force (F), be taken as fundamental quantities, then what are the dimensions of mass :- (1) EV2 (2) EV–2 (3) FV–1 (4) FV–2 51. A system has basic dimensions as density [D], velocity [V] and area [A]. The dimensional representation of force in this system is :- (1) AV2D (2) A2VD (3) AVD2 (4) A0VD ERRORS 52. The significant digits in 200.40 are :- (1) 4 (2) 5 (3) 2 (4) 3 53. Number of significant digits in 0.01230 is :- (1) 3 (2) 4 (3) 5 (4) 6 54. Which of the following has the highest number of significant figures ? (1) 0.007 m2 (2) 2.64 × 1024 kg (3) 0.0006032 m2 (4) 6.3200 J 55. Given P = 0.0030 m, Q = 2.40 m and R = 3000m, the number of significant figures in P, Q and R are respectively :- (1) 1, 2, 1 (2) 2, 3, 4 (3) 4, 2, 1 (4) 4, 2, 4 56. After rounding off the number 4621 to 2 significant digits the value becomes :- (1) 4600 (2) 4500 (3) 4700 (4) 4720
NEET : Physics [ 102 ] www.allendigital.in  Digital 57. If L = 2.331 cm and B = 2.1 cm, then L + B = (According to significant figures) (1) 4.431 cm (2) 4.43 cm (3) 4.4 cm (4) 4 cm 58. Subtract 0.2 J from 5.27 J and express the result with correct number of significant figures :- (1) 5.1 J (2) 5.06 J (3) 5.0 J (4) 5 J 59. In arithmetic 17.8 × 3.1143 = 55.4354. But as a result of experimental measurements the best way to express the product is :- (1) 55.3454 (2) 55.4 (3) 55.44 (4) 55.435 60. The order of magnitude of the number 1013 is:- (1) 1 (2) 2 (3) 3 (4) 4 61. The length of a rod is (11.05 ± 0.05) cm. What is the sum of lengths of two such rods :- (1) (22.1 ± 0.05) cm (2) (22.10 ± 0.05) cm (3) (22.1 ± 0.15) cm (4) (22.10 ± 0.10) cm 62. The external and internal radius of a hollow cylinder are measured to be (5.23 ± 0.015) cm and (4.89 ± 0.005) cm. The thickness of the wall of the cylinder is :- (1) (0.34 0.02) cm (2) (0.17 0.02) cm (3) (0.17 0.01) cm (4) (0.34 0.01) cm 63. The resistance is V R I = where V = (100 ± 5) volt and I = (10 ± 0.2) ampere. What is the total error in R ? (1) 5 % (2) 7 % (3) 5.2 % (4) 5 2       % 64. When a copper sphere is heated, maximum percentage change will be observed in– (1) radius (2) area (3) volume (4) none of these 65. If error in measuring diameter of a circle is 2%, the error in circumference of the circle would be :- (1) 2% (2) 8% (3) 4% (4) 1% 66. The error is the measurement of volume of sphere is 1.5%. The error in the measurement of its diameter is :- (1) 1% (2) 2% (3) 0.5% (4) 1.5% 67. There is an error of 2% in the measurement of side of a cube. The percentage error in the calculation of its volume will be :- (1) 1% (2) 2% (3) 3 (4) 6% 68. A thin copper wire of length  metre increases in length by 2% when heated through 10°C. What is the percentage increase in area when a square copper sheet of length  metre is heated through 10°C ? (1) 4% (2) 8% (3) 16% (4) None of these 69. If f = x2, then the relative error in f is :- (1) 2 x x  (2)  2 ( x) x (3) x x  (4) (x)2 70. The percentage error in the measurement of mass and speed are 2% and 3% respectively. How much will be the maximum error in the estimate of kinetic energy obtained by measuring mass and speed :- (1) 11% (2) 8% (3) 5% (4) 4% 71. The heat generated in a circuit is dependent upon the resistance, current and time for which the current is flown. If the error in measuring the above are as 1%, 2% and 1% the maximum error in measuring heat will be (1) 2% (2) 3% (3) 6% (4) 1% 72. Percentage error in measuring the radius (R) and mass (M) of a solid sphere are 2% & 1% respectively. Then error in measurement of moment of inertia about to its diameter   =     2 2 i.e. I MR 5 is :- (1) 3 % (2) 6 % (3) 5 % (4) 4 % 73. The resistance R of a wire is given by the relation R =   2 r . Percentage error in the measurement of ,  and r is 1%, 3 % and 2% respectively. Then the percentage error in the measurement of R is (1) 6% (2) 9% (3) 8% (4) 10%