Physics Fluid Dynamics PMDC Conceptual Practice
PMDC Verified Question 29 of 37
As an object accelerates and moves faster through a viscous fluid, what happens to the magnitude of the retarding drag force it experiences?
A
It decreases linearly.
B
It increases.
C
It remains entirely constant.
D
It decreases exponentially.
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: It increases.
Concept:

Drag forces are velocity-dependent frictional forces. A faster object disturbs the fluid more aggressively.

Formula:

$$ F \propto v \quad \text{(low speed)} \quad \text{or} \quad F \propto v^2 \quad \text{(high speed)} $$

Solution:

  • Whether an object is moving slowly (governed by Stokes' law, \( F \propto v \)) or rapidly (governed by the drag equation, \( F \propto v^2 \)), the drag force is a directly increasing function of velocity.
  • Therefore, as the object's speed increases, the drag force it experiences must inherently increase.


Why other options are incorrect:

Drag forces never decrease or remain constant when speed increases; fluid resistance universally scales upward with velocity.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

Previous Question All Fluid Dynamics MCQs Next Question

Want to solve full-length papers under timed exam conditions?

Practice with zero-scroll lockdown sprints, dynamic latency zone timers, live peer selection telemetry, and the automated Amber mistake recovery loop.

Enter Arena Sprint iOS App Android App