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Units and Measurements

JEE Main 2026 (Online) 28th January Evening ShiftMCQEasy📈 Topic in 33% papers+4−1
Ques. 1JEE Main 2026, 28 January (Evening Shift)

The time period of a simple harmonic oscillator is T = 2 mk. Measured value of mass (m) of the object is 10 g with an accuracy of 10 mg and time for 50 oscillations of the spring is found to be 60 s using a watch of 2 s resolution. Percentage error in determination of spring constant (k) is %.

  1. 3.43
  2. 7.60
  3. 3.35
  4. 6.76

Answer

(4) 6.76

Solution

T = 2 mk k = 4 2 mT2

kk 100 = mm 100 + 2 TT 100

mm 100 = 10 mg10 g 100 = 0.0110 100 = 0.1\%

TT = tt = 260 (t = time for 50 oscillations) TT 100 = 3.33\%

kk 100 = 0.1\% + 2 3.33\% = 6.76\%

Answer: (4)

Keep practising — Units and Measurements

Ques. 2JEE Main 2026, 28 January (Evening Shift)

Match List - I with List - II. Choose the correct answer from the options given below :

  1. A-I, B-II, C-IV, D-III
  2. A-IV, B-III, C-I, D-II
  3. A-IV, B-I, C-II, D-III
  4. A-I, B-III, C-II, D-IV
Ques. 3JEE Main 2026, 28 January (Evening Shift)

In an experiment, a set of readings are obtained as follows: 1.24 mm, 1.25 mm, 1.23 mm, 1.21 mm. The expected least count of the instrument used in recording these readings is mm.

  1. 0.01
  2. 0.05
  3. 0.001
  4. 0.1
Ques. 4JEE Main 2026, 24 January (Morning Shift)

Match the LIST-I with LIST-II Choose the correct answer from the options given below:

  1. A-III, B-IV, C-II, D-I
  2. A-I, B-III, C-IV, D-II
  3. A-IV, B-III, C-I, D-II
  4. A-III, B-IV, C-I, D-II
Ques. 5JEE Main 2026, 24 January (Evening Shift)

In a vernier callipers, 50 vernier scale divisions are equal to 48 main scale divisions. If one main scale division = 0.05 mm, then the least count of the vernier callipers is mm.

  1. 0.002
  2. 0.02
  3. 0.05
  4. 0.005
Ques. 6JEE Main 2026, 23 January (Morning Shift)

In a screw gauge, the zero of the circular scale lies 3 divisions above the horizontal pitch line when their metallic studs are brought in contact. Using this instrument thickness of a sheet is measured. If pitch scale reading is 1 mm and the circular scale reading is 51 then the correct thickness of the sheet is mm. [Assume least count is 0.01 mm]

  1. 1.54
  2. 1.50
  3. 1.51
  4. 1.48
Ques. 7JEE Main 2026, 23 January (Morning Shift)

Four persons measure the length of a rod as 20.00 cm, 19.75 cm, 17.01 cm and 18.25 cm. The relative error in the measurement of average length of the rod is :

  1. 0.18
  2. 0.24
  3. 0.06
  4. 0.08
Ques. 8JEE Main 2026, 23 January (Evening Shift)

A ball of radius r and density dropped through a viscous liquid of density and viscosity attains its terminal velocity at time t, given by t = A a rb c d, where A is a constant and a, b, c and d are integers. The value of b + ca + d is .

Ques. 9JEE Main 2026, 22 January (Morning Shift)

Match the LIST-I with LIST-II Choose the correct answer from the options given below:

  1. A-III, B-II, C-IV, D-I
  2. A-I, B-IV, C-II, D-III
  3. A-II, B-I, C-IV, D-III
  4. A-II, B-IV, C-I, D-III
Ques. 10JEE Main 2026, 21 January (Morning Shift)

In an experiment the values of two spring constants were measured as k1 = (10 0.2) N/m and k2 = (20 0.3) N/m. If these springs are connected in parallel, then the percentage error in equivalent spring constant is :

  1. 1.33%
  2. 2.67%
  3. 1.67%
  4. 2.33%
Ques. 11JEE Main 2026, 21 January (Morning Shift)

Consider a modified Bernoulli equation. (P + ABt2 ) + g(h + Bt) + 12 V2 = constant If t has the dimension of time then the dimensions of A and B are , respectively.

  1. [ ML0T-1] and [M0LT]
  2. [ ML0T-2] and [ M0LT-1]
  3. [ ML0T-2] and [ M0LT-2]
  4. [ ML0T-1] and [ M0LT-1]

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