Physics Work & Energy NUMS 2022
PMDC Verified Question 62 of 108
If the speed of a body is doubled, its kinetic energy become:
A
\( mv^2 \)
B
\( 2mv^2 \)
C
\( 16mv^2 \)
D
\( 4mv^2 \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: \( 2mv^2 \)
Concept:

Calculate the actual mathematical expression for the new kinetic energy, not just the multiplication factor.

Formula:

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

Solution:

  • Let initial K.E = \( \frac{1}{2}mv^2 \).


  • Substitute \( 2v \) for the new speed: New K.E = \( \frac{1}{2}m(2v)^2 \).


  • New K.E = \( \frac{1}{2}m(4v^2) \).


  • Simplify the fraction: \( \left(\frac{4}{2}\right)mv^2 = 2mv^2 \).


Why other options are incorrect:

Students often memorize "it increases by 4 times" and mistakenly select \( 4mv^2 \) (Option D), forgetting the initial \( 1/2 \) coefficient.

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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