Physics Fluid Dynamics PMDC Conceptual Practice
PMDC Verified Question 26 of 37
A small leak develops in the wall of a large outdoor water storage tank. If the surface level of the water is \( 10 \text{ m} \) vertically above the leak, what is the speed of the water efflux? (Use \( g = 9.8 \text{ m/s}^2 \))
A
\( 9.8 \text{ m/s} \)
B
\( 10 \text{ m/s} \)
C
\( 14 \text{ m/s} \)
D
\( 20 \text{ m/s} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: \( 14 \text{ m/s} \)
Concept:

Torricelli's Law dictates the speed at which liquid escapes a container through a small orifice.

Formula:

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

Solution:

  • We are given the depth \( h = 10 \text{ m} \) and gravity \( g = 9.8 \text{ m/s}^2 \).
  • Substitute the values: \( v = \sqrt{2 \times 9.8 \times 10} \).
  • \( v = \sqrt{19.6 \times 10} = \sqrt{196} \).
  • The square root of 196 is exactly 14. Therefore, \( v = 14 \text{ m/s} \).


Why other options are incorrect:

Option A is just the value of gravity. Option D (20 m/s) would be the answer if you calculated \( \sqrt{400} \), missing the actual multiplication.

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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