Question:
A copper ball of radius r is moving with a uniform velocity v in the mustard oil and the dragging force acting on the ball is F. The dragging force on the copper ball of radius 2r with uniform velocity 2v in the mustard oil is
A copper ball of radius r is moving with a uniform velocity v in the mustard oil and the dragging force acting on the ball is F. The dragging force on the copper ball of radius 2r with uniform velocity 2v in the mustard oil is
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Stokes' law: drag force $F \propto r v$ for a sphere in viscous fluid.
Updated On: Apr 16, 2026
- F
- 2F
- 4F
- 8F
Show Solution
Verified By Collegedunia
The Correct Option is D
Solution and Explanation
Step 1: Stokes' law: $F = 6πη r v$.
Step 2: For $r' = 2r$, $v' = 2v$, $F' = 6πη (2r)(2v) = 8 × 6πη rv = 8F$.
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