The viscous drag on a small spherical body (moving with slow speed v) is proportional to
Correct answer: A. v
- A. v
- B. √v
- C. 1/√v
- D. v2
Explanation
The correct answer is v. According to Stokes' Law, the viscous drag force experienced by a small spherical object moving slowly through a viscous fluid is directly proportional to its velocity. This is a key concept in fluid dynamics for low Reynolds number conditions, where the flow is laminar. Option A is correct as it correctly reflects this relationship. Options B, C, and D are incorrect because they do not align with the principles of Stokes' Law. Option B suggests a square root dependency, which is not applicable in this context. Option C implies an inverse relationship, which is incorrect, and Option D describes a quadratic relationship more typical of turbulent flows, not the slow speeds described in the question.
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About Fluid Dynamics
Fluid flow is described through speed, pressure and density, including steady flow and the equation of continuity for conserving mass. Bernoulli's equation relates pressure, speed and height, while fluid drag and terminal velocity explain why a falling object eventually moves at constant speed when drag balances its weight.
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