Oscillations (SHM) · JEE Main previous year questions

2020 5 questions

1. Q262020 · 3 Sept 2020 · Shift 2

   A block of mass m attached to a massless spring is performing oscillatory motion of amplitude 'A' on a frictionless horizontal plane. If half of the mass of the block breaks off when it is passing through its equilibrium point, the amplitude of oscillation for the remaining system become $f\mathrm{A}$. The value of $f$ is :

   1. A.1
   2. B.$\frac{1}{2}$
   3. C.$\sqrt{2}$
   4. D.$\frac{1}{\sqrt{2}}$
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   Answer: D

2. Q332020 · 9 Jan 2020 · Shift 2

   A small circular loop of conducting wire has radius a and carries current I. It is placed in a uniform magnetic field B perpendicular to its plane such that when rotated slightly about its diameter and released, it starts performing simple harmonic motion of time period T. If the mass of the loop is m then :

   1. A.$T=\sqrt{\frac{2m}{IB}}$
   2. B.$T=\sqrt{\frac{\pi m}{IB}}$
   3. C.$T=\sqrt{\frac{\pi m}{2IB}}$
   4. D.$T=\sqrt{\frac{2\pi m}{IB}}$
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   Answer: D

3. Q312020 · 8 Jan 2020 · Shift 2

   A simple pendulum is being used to determine the value of gravitational acceleration g at a certain place. The length of the pendulum is 25.0 cm and a stop watch with 1s resolution measures the time taken for 40 oscillations to be 50 s. The accuracy in g is :

   1. A.4.40%
   2. B.3.40%
   3. C.2.40%
   4. D.5.40%
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   Answer: A

4. Q402020 · 7 Jan 2020 · Shift 1

   A LCR circuit behaves like a damped harmonic oscillator. Comparing it with a physical spring-mass damped oscillator having damping constant 'b', the correct equivalence would be:

   1. A.$\mathrm{L}\leftrightarrow \mathrm{k},\mathrm{C}\leftrightarrow \mathrm{b},\mathrm{R}\leftrightarrow \mathrm{m}$
   2. B.$\mathrm{L}\leftrightarrow \mathrm{m},\mathrm{C}\leftrightarrow \mathrm{k},\mathrm{R}\leftrightarrow \mathrm{b}$
   3. C.$\mathrm{L}\leftrightarrow \mathrm{m},\mathrm{C}\leftrightarrow \frac{1}{k},\mathrm{R}\leftrightarrow \mathrm{b}$
   4. D.$\mathrm{L}\leftrightarrow \frac{1}{b},\mathrm{C}\leftrightarrow \frac{1}{m},\mathrm{R}\leftrightarrow \frac{1}{k}$
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   Answer: C

5. Q412020 · 7 Jan 2020 · Shift 2

   A box weight 196 N on a spring balance at the north pole. Its weight recorded on the same balance if it is shifted to the equator is close to (Take $\text{g}=10{\text{ ms}}^{-2}$ at the north pole and the radius of the earth $=6400\text{ km}$) :

   1. A.194.32 N
   2. B.195.66 N
   3. C.195.32 N
   4. D.194.66 N
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   Answer: C