Physics Fluid Dynamics PMDC Conceptual Practice
PMDC Verified Question 27 of 37
A thin horizontal plate with an area of \( 0.05 \text{ m}^2 \) lies perfectly flat beneath the surface of a liquid having a density of \( 1000 \text{ kg/m}^3 \). If the downward force on the plate due strictly to liquid pressure is \( 490 \text{ N} \), what is the depth of the plate? (Use \( g = 9.8 \text{ m/s}^2 \))
A
\( 1.0 \text{ m} \)
B
\( 0.5 \text{ m} \)
C
\( 1.5 \text{ m} \)
D
\( 2.0 \text{ m} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: \( 1.0 \text{ m} \)
Concept:

Hydrostatic pressure relies on fluid depth. Pressure is the force exerted per unit area.

Formula:

$$ P = \frac{F}{A} \quad \text{and} \quad P = \rho g h $$

Solution:

  • First, calculate the hydrostatic pressure on the plate: \( P = \frac{490}{0.05} \).
  • \( P = \frac{490}{1/20} = 490 \times 20 = 9800 \text{ Pa} \).
  • Next, relate pressure to depth: \( 9800 = \rho g h \).
  • \( 9800 = (1000)(9.8)h \).
  • \( 9800 = 9800 h \implies h = 1.0 \text{ m} \).


Why other options are incorrect:

Dividing or multiplying incorrectly at the \( 490/0.05 \) step leads to massive errors, making the depth seem excessively shallow or deep.

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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