Spherical balls of radius $r$ are falling in a viscous fluid of viscosity $\eta$ with a velocity $v$. The retarding viscous force acting on the spherical ball is

  • A
    Inversely proportional to $r$ but directly proportional to velocity $v$
  • B
    Directly proportional to both radius $r$ and velocity $v$
  • C
    Inversely proportional to both radius $r$ and velocity $v$
  • D
    Directly proportional to $r$ but inversely proportional to $v$

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