WBJEE 2021 Question Paper with Solution PDFs Available- Download Here

WBJEE 2021 Questions

• 1.

  Which logic gate is represented by the following combination of logic gates?

  

  • NAND
  • AND
  • NOR
  • OR
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• 2.

  Ruma reached the metro station and found that the escalator was not working. She walked up the stationary escalator with velocity \( v_1 \) in time \( t_1 \). On another day, if she remains stationary on the escalator moving with velocity \( v_2 \), the escalator takes her up in time \( t_2 \). The time taken by her to walk up with velocity \( v_1 \) on the moving escalator will be:

  • \( \frac{t_1}{t_2} \)
  • \( \frac{t_1 + t_2}{t_2 - t_1} \)
  • \( \frac{t_1 + t_2}{v_1 + v_2} \)
  • \( \frac{t_1 t_2}{t_1 + t_2} \)
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• 3.

  The variation of displacement with time of a simple harmonic motion (SHM) for a particle of mass \( m \) is represented by: \[ y = 2 \sin \left( \frac{\pi}{2} + \phi \right) \, \text{cm} \] The maximum acceleration of the particle is:

  • \( \frac{\pi^2}{2} \, \text{cm/sec}^2 \)
  • \( \frac{\pi}{2m} \, \text{cm/sec}^2 \)
  • \( \frac{\pi^2}{2m} \, \text{cm/sec}^2 \)
  • \( \frac{\pi^2}{2} \, \text{cm/sec}^2 \)
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• 4.

  A force \( \mathbf{F} = ai + bj + ck \) is acting on a body of mass \( m \). The body was initially at rest at the origin. The co-ordinates of the body after time \( t \) will be:

  • \( \frac{ar^2}{2m} i + \frac{br^2}{2m} j + \frac{cr^2}{2m} k \)
  • \( \frac{ar^2}{2m} i + \frac{br^2}{2m} j + \frac{cr^2}{2m} k \)
  • \( \frac{ar}{m} i + \frac{br}{m} j + \frac{cr}{m} k \)
  • \( \frac{ar}{m} i + \frac{br}{m} j + \frac{cr}{m} k \)
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• 5.

  A quantity \( X \) is given by: \[ X = \frac{\epsilon_0 L \Delta V}{\Delta t} \] where:
  - \( \epsilon_0 \) is the permittivity of free space,
  - \( L \) is the length,
  - \( \Delta V \) is the potential difference,
  - \( \Delta t \) is the time interval.
  The dimension of \( X \) is the same as that of:

  • Resistance
  • Charge
  • Voltage
  • Current
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