Physics Work & Energy ETEA 2023
PMDC Verified Question 30 of 108
Which of the following bodies has the largest kinetic energy?
A
Mass 3M and speed v
B
Mass 3M and speed 2v
C
Mass 3M and speed 3v
D
Mass M and speed 4v
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Mass 3M and speed 3v
Concept:

Kinetic energy scales linearly with mass but quadratically with speed. Calculate the relative coefficient for each option.

Formula:

$$ K.E = \frac{1}{2}mv^2 $$

Solution:

  • Calculate coefficients relative to \( Mv^2 \):


  • Option A: \( \frac{1}{2}(3)(1)^2 = 1.5 \)


  • Option B: \( \frac{1}{2}(3)(2)^2 = \frac{1}{2}(3)(4) = 6 \)


  • Option C: \( \frac{1}{2}(3)(3)^2 = \frac{1}{2}(3)(9) = 13.5 \)


  • Option D: \( \frac{1}{2}(1)(4)^2 = \frac{1}{2}(16) = 8 \)


  • 13.5 is the largest coefficient, making Option C the greatest kinetic energy.


Why other options are incorrect:

Option D seems intuitively large due to the high speed (4v), but the heavier mass (3M) in Option C combined with a high speed (3v squared = 9) overcomes it.

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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