A) directly proportional to \[R\] but inversely proportional to\[v\]
B) directly proportional to both radius \[R\] and velocity\[v\]
C) inversely proportional to both radius \[R\] and velocity\[v\]
D) inversely proportional to \[R\] but directly proportional to velocity\[v\]
Correct Answer: B
Solution :
Retarding force acting on a ball falling into a viscous fluid \[F=6\pi \eta Rv\] where \[R=\]radius of ball, \[v=\] velocity of ball, and \[\eta =\]coefficient of viscosity. \[\therefore \] \[F\propto R\]and\[F\propto v\] Or in words, retarding force is directly proportional to both \[R\] and \[v\].You need to login to perform this action.
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