{"id":47188,"date":"2024-02-17T08:01:09","date_gmt":"2024-02-17T02:31:09","guid":{"rendered":"https:\/\/www.aplustopper.com\/?p=47188"},"modified":"2024-02-17T16:14:30","modified_gmt":"2024-02-17T10:44:30","slug":"plus-one-physics-chapter-wise-questions-answers-chapter-2","status":"publish","type":"post","link":"https:\/\/www.aplustopper.com\/plus-one-physics-chapter-wise-questions-answers-chapter-2\/","title":{"rendered":"Plus One Physics Chapter Wise Questions and Answers Chapter 2 Units and Measurement"},"content":{"rendered":"

Kerala Plus One Physics Chapter Wise Questions and Answers Chapter 2 Units and Measurement<\/h2>\n

Plus One Physics Units and Measurement One Mark Questions and Answers<\/h3>\n

Question 1.
\nHow many seconds are there in a light fermi?
\n(a) 10-15<\/sup>
\n(b) 3.0 \u00d7 108<\/sup>
\n(c) 3.33 \u00d7 10-24<\/sup>
\n(d) 3.3 \u00d7 10-7<\/sup>
\nAnswer:
\n(c) 3.33 \u00d7 10-24<\/sup>
\nOne light fermi is time taken by light to travel a distance of 1 fermi ie. 10-15<\/sup>m
\n1 light fermi = \\(\\frac{10^{-15}}{3 \\times 10^{8}}\\) = 3.33 \u00d7 10-24<\/sup>s.<\/p>\n

Question 2.
\nWhich of the following pairs have same dimensional formula for both the quantities?<\/p>\n

    \n
  1. Kinetic energy and torque<\/li>\n
  2. Resistance and Inductance<\/li>\n
  3. Young\u2019s modulus and pressure<\/li>\n<\/ol>\n

    (a) (1)only
    \n(b) (2) only
    \n(c) (1) and (3) only
    \n(d) All of three
    \nAnswer:
    \n(c) (1) and (3) only<\/p>\n

    Question 3.
    \nGive four dimensionless physical quantities.
    \nAnswer:
    \nAngle, Poisson\u2019s ratio, strain, specific gravity.<\/p>\n

    Question 4.
    \nThe dimensions of plank constant are the same as those of______.
    \nAnswer:
    \nAngular momentum<\/p>\n

    Question 5.
    \nA physical quantity P = \\(\\frac{\\sqrt{a b c^{2}}}{d^{3}}\\) measuring a, b, c and d separately with the percentage error of 2% , 3%, 2% and 1% respectively. Minimum amount of error is contributed by the measurement of
    \n(a) b
    \n(b) a
    \n(c) d
    \n(d) c
    \nAnswer:
    \n(b) a
    \nP = \\(\\frac{\\sqrt{a b c^{2}}}{d^{3}}\\)
    \n\"Plus
    \nThe minimum amount of error is contributed by the measurement of a.<\/p>\n

    Question 6.
    \nThe number of significant figures in 11.118 \u00d7 10-6<\/sup> is
    \n(a) 3
    \n(b) 6
    \n(c) 5
    \n(d) 4
    \nAnswer:
    \nAs per rules, number of significant figures in 11.118 \u00d7 10-6<\/sup> is 5.<\/p>\n

    Question 7.
    \nWhat is the number of significant figures in 0.06070?
    \nAnswer:
    \n4.<\/p>\n

    Question 8.
    \nIf f = x2<\/sup>, What is the relative error in f?
    \nAnswer:
    \n\\(\\frac{2 \\Delta x}{x}\\).<\/p>\n

    Question 9.
    \nWhich of the following measurement is more accu\u00acrate?
    \n(i) 7000m
    \n(ii) 7 \u00d7 102<\/sup>m
    \n(iii) 7 \u00d7 103<\/sup>m
    \nAnswer:
    \n(i) 7000 m<\/p>\n

    Question 10.
    \nWhich of the following measurements is most, accurate?
    \n(a) 5.0 cm
    \n(b) 0.005 cm
    \n(c) 5.00 cm
    \nAnswer:
    \n(c) Is most accurate because it has three significant figures. Greater is number of significant figures, more accurate is the measurement.
    \n(a) has 2 significant figures
    \n(b) has 1 significant figure.<\/p>\n

    Question 11.
    \nName three physical quantities having same dimension.
    \nAnswer:
    \nWork, Energy, and Torque.<\/p>\n

    Plus One Physics Units and Measurement Tw0 Mark Questions and Answers<\/h3>\n

    Question 1.
    \nUsing dimensional analysis derive the relation F = ma. Where the symbols have the usual meaning.
    \nAnswer:
    \nForce on a body depends on mass(m), acceleration (a) an
    \nF \u03b1 ma<\/sup>ab<\/sup>tc<\/sup>
    \nM1<\/sup>L1<\/sup>T-2<\/sup> = Ma<\/sup>(LT-2<\/sup>)b<\/sup>Tc<\/sup>
    \nM1<\/sup>L1<\/sup>T-2<\/sup> = Ma<\/sup>Lb<\/sup>T-2a+c<\/sup>
    \nEquating the powers, we get a = 1 ,b = 1, -2b + c = -2, c = 0
    \nF = m1<\/sup>a1<\/sup>t0<\/sup> = ma.<\/p>\n

    Question 2.
    \nUse your definition to explain how simple harmonic motion can be represented by the equation y = a sin \u03c9t
    \n(a) Show that the above equation is dimensionally correct
    \nAnswer:
    \nY = a sin \u03c9t
    \nsin \u03c9t has no dimensions. Hence we get L = L
    \nHence this equation is dimensionaly correct.
    \n\"Plus<\/p>\n

    Question 3.
    \nFill in the blanks.<\/p>\n

      \n
    1. The curved surface area of a solid cylinder of radius 2 cm and height 20 cm is_____m2<\/sup> (Write answer in 3 significant digits)<\/li>\n
    2. Im = ______ ly<\/li>\n<\/ol>\n

      Answer:
      \n1. Curved area = 2\u03c0l
      \n= 2 \u00d7 3.14 (2 \u00d7 102<\/sup>) \u00d7 20 \u00d7 102<\/sup>
      \n= 2.51 \u00d7 10-6<\/sup>m2<\/sup><\/p>\n

      2. l ly= 9.46 \u00d7 1015<\/sup> m
      \nlm = \\(\\frac{l \\mathrm{ly}}{9.46 \\times 10^{15}}\\) \u2248 10-6<\/sup>ly.<\/p>\n

      Question 4.<\/p>\n

        \n
      1. Give a physical quantity with a unit and no dimension.<\/li>\n
      2. Arrange the following in the descending order.
        \n1 light year, 1 parsec, 1 astronomical unit<\/li>\n<\/ol>\n

        Answer:<\/p>\n

          \n
        1. Angle has no dimension. But it has unit.<\/li>\n
        2. 1 parsec, 1 light year, 1 astronomical unit.<\/li>\n<\/ol>\n

          Question 5.
          \nMagnitude of force F experienced by a certain object moving with speed V is given by F = KV2<\/sup>. Where K is a constant. Find the dimensions of K.
          \nAnswer:
          \nF = KV2<\/sup>
          \n\"Plus<\/p>\n

          Question 6.
          \nWhat is the maximum percentage error in the measurement of kinetic energy if percentage errors in mass and speed are 2% and 3% respectively?
          \nAnswer:
          \nE = \\(\\frac{1}{2}\\)v2<\/sup>
          \n\"Plus
          \n% error in KE = % error in mass + 2 \u00d7 % error in speed
          \n= 2% + 2 \u00d7 3% = 8%.<\/p>\n

          Question 7.
          \nSolve the following with regard to significant figures.<\/p>\n

            \n
          1. 5.8 + 0.125<\/li>\n
          2. 3.9 \u00d7 105<\/sup> – 2.5 \u00d7 104<\/sup><\/li>\n<\/ol>\n

            Answer:
            \n1. 5.8 + 0.125 = 5.925
            \nRounding to first decimal point, we get 5.9<\/p>\n

            2. 3.9 \u00d7 105<\/sup> – 2.5 \u00d7 104<\/sup>
            \n= 3.5 \u00d7 105<\/sup> – 0.25 \u00d7 104<\/sup>
            \n= 3.65 \u00d7 105<\/sup>
            \nRounding to first decimal place, we get 3.6 \u00d7 105<\/sup>.<\/p>\n

            Question 8.
            \nWhat is maximum fractional error in
            \ni) (a + b)
            \nii) a – b
            \niii) ab
            \niv) \\(\\frac{a}{b}\\)
            \nGiven \u2206 a and \u2206 b are absolute errors in measurements a and b.
            \nAnswer:
            \n\"Plus<\/p>\n

            Question 9.<\/p>\n

              \n
            1. What is the fractional error in an<\/sup>? (Given absolute error in a is \u2206 a)<\/li>\n
            2. What is absolute error in the measurements according to least count?\n