Physics Work & Energy DUHS 2022
PMDC Verified Question 55 of 108
If mass and speed of a moving object is doubled, the K.E will be:
A
Eight times
B
Four times
C
Doubled
D
Sixteen times
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Eight times
Concept:

Kinetic energy is linearly proportional to mass and quadratically proportional to velocity.

Formula:

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

Solution:

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


  • New mass \( m' = 2m \). New speed \( v' = 2v \).


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


  • \( E' = \frac{1}{2}(2m)(4v^2) = 8 \times \left(\frac{1}{2}mv^2\right) \).


  • \( E' = 8E \). It becomes eight times greater.


Why other options are incorrect:

If only speed is doubled, it's 4 times. If only mass is doubled, it's 2 times. If both were squared, it would be 16 times.

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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