Physics Force & Motion BUMHS 2024
PMDC Verified Question 19 of 137
A 40kg body starting from rest falls through a vertical distance of 125cm to ground. The velocity of the body just before it hits the ground is:
A
\( 250 \text{ m/s} \)
B
\( (250) \text{ m/s} \)
C
\( 25 \text{ m/s} \)
D
\( 5 \text{ m/s} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: \( 5 \text{ m/s} \)
Concept:

Energy conservation or the third equation of kinematics, heavily relying on strict unit conversion.

Formula:

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

Solution:

  • Mass is irrelevant for free fall speed.


  • CRITICAL: Convert height from cm to meters. \( h = 125 \text{ cm} = 1.25 \text{ meters} \).


  • Use gravity \( g = 10 \text{ m/s}^2 \) (standard estimation).


  • $$ v = \sqrt{2 \times 10 \times 1.25} $$


  • $$ v = \sqrt{25} = 5 \text{ m/s} $$


Why other options are incorrect:

If a student forgets to convert cm to meters, they calculate \( \sqrt{2 \times 10 \times 125} = \sqrt{2500} = 50 \). If they didn't square root properly, they might land on 25. The 40kg mass is purely a distractor.

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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