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Mechanical Properties of Fluids — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysicsMechanical Properties of Fluids1 Mark
MCQ
For a ball falling in a liquid with constant velocity, ratio of resistance force due to the liquid to that due to gravity is:
  • ✓
    $1$
  • B
    $\frac29\frac{\text{a}^2\rho\text{g}}{\eta^2}$
  • C
    $\frac29\frac{\text{a}^2(\rho-\sigma)\text{g}}{\eta}$
  • D
    None of these.
✓

Answer

Correct option: A.
$1$
When a body while falling in a viscous liquid moves with a constant velocity $($i.e., attains terminal velocity$),$ the resultant force on the body is zero.
So the viscous force acting upwards is equal to the gravity pull acting downwards.

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