1
JEE Main 2026 (Online) 28th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The time period of a simple harmonic oscillator is $T = 2\pi \sqrt{\frac{k}{m}}$. 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 ________%.

A

3.43

B

7.60

C

3.35

D

6.76

2
JEE Main 2026 (Online) 28th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The speed of a longitudinal wave in a metallic bar is 400 m/s. If the density and Young's modulus of the bar material are increased by 0.5% and 1%, respectively then the speed of the wave is changed approximately to ______ m/s.

A

398

B

402

C

401

D

399

3
JEE Main 2026 (Online) 28th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Match List - I with List - II.

List – I List – II
A.  Coefficient of viscosity

B.  Surface tension

C.  Pressure

D.  Surface energy
I.  [ML−1T−2]

II.  [ML2T−2]

III.  [ML0T−2]

IV.  [ML−1T−1]

Choose the correct answer from the options given below :

A

A-I, B-II, C-IV, D-III

B

A-IV, B-III, C-I, D-II

C

A-IV, B-I, C-II, D-III

D

A-I, B-III, C-II, D-IV

4
JEE Main 2026 (Online) 28th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

In an experiment, a set of reading 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.

A

0.01

B

0.05

C

0.001

D

0.1

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