Q149 / 155 · WBJEE 2024 · Physics

A metal plate of area $10^{-2} \mathrm{~m}^2$ rests on a lauer of castor oil, $2 \times 10^{-3} \mathrm{~m}$ thick whose coefficient of viscosity is $1.55 ~Ns~ m^{-2}$. The approximate horizontal force required to move the plate with a uniform speed of $3 \times 10^{-2} \mathrm{~ms}^{-1}$ is

  • A
    0.6718 N
  • Correct answer
    B
    0.2325 N
  • C
    0.2022 N
  • D
    0.6615 N

Solution

Hint: $\quad F=\eta \mathrm{A} \frac{\mathrm{v}}{\mathrm{h}}=1.55 \times 10^{-2} \times \frac{3 \times 10^{-2}}{2 \times 10^{-3}}$

Hence, the correct answer is option: 'B'.

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