Physics Fluid Dynamics PMDC Conceptual Practice
PMDC Verified Question 32 of 37
An incompressible, non-viscous liquid is filled in a large container. A small puncture is made at a vertical depth of \( 5.0 \text{ m} \) below the liquid's completely free surface. Assuming \( g = 10 \text{ m/s}^2 \), what is the speed of efflux from the puncture?
A
\( 5 \text{ m/s} \)
B
\( 10 \text{ m/s} \)
C
\( 25 \text{ m/s} \)
D
\( 50 \text{ m/s} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: \( 10 \text{ m/s} \)
Concept:

Torricelli's Law applies to the fluid escaping from a hole at a specified depth, mathematically behaving like an object dropped in free fall.

Formula:

$$ v = \sqrt{2gh} $$

Solution:

  • Given the depth from the surface \( h = 5.0 \text{ m} \) and gravity \( g = 10 \text{ m/s}^2 \).
  • Plug into the equation: \( v = \sqrt{2 \times 10 \times 5} \).
  • \( v = \sqrt{100} \).
  • \( v = 10 \text{ m/s} \).


Why other options are incorrect:

Option D (50 m/s) comes from multiplying \( 10 \times 5 \) but forgetting the multiplier 2 and the square root. Option C incorrectly assumes \( v^2 / 2 \).

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.

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