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Most Important Selected Qs for JEE AdvancedPhysicsMechanical Properties of Fluids

A hollow cylinder of radius R and height h ( R ) is completely filled with a liquid having coefficient of viscosity . Now a cylinder of radius R is placed over it and is rotated with constant angular velocity by an external agent as shown.

Options

  1. ANet viscous force acting on the cylinder is zero.
  2. Bexternal torque required to rotate the cylinder with constant angular velocity is R^4 h .
  3. Cexternal torque required to rotate the cylinder with constant angular velocity is R^4 2 h .
  4. Dexternal power required to rotate the cylinder with constant angular velocity is ^2 R^4 h .

Correct answer

C. external torque required to rotate the cylinder with constant angular velocity is R^4 2 h .

Step-by-step solution

aligned & d = [ x h 2 x d x ] x= 2 h x^3 d x & = d = R^4 2 h P= = ^2 R^4 2 h aligned

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