Physics Rotational & Circular Motion ETEA 2017
PMDC Verified Question 85 of 95
A centripetal force F acts on a body moving with angular speed \( \omega \). If the angular speed is tripled, then the magnitude of centripetal force becomes:
A
\( 8 F \)
B
\( 9 F \)
C
\( 3 F \)
D
\( 4 F \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: \( 9 F \)
Concept:

Centripetal force can be expressed in terms of angular velocity. The relationship reveals that the force scales with the square of the angular velocity.

Formula:

$$ F_c = mr\omega^2 $$

Solution:

  • Let the initial force be \( F = mr\omega^2 \).
  • If the new angular speed is \( \omega' = 3\omega \), substitute this into the formula.
  • \( F' = mr(3\omega)^2 = mr(9\omega^2) = 9(mr\omega^2) \).
  • Therefore, the new force is \( 9F \).


Why other options are incorrect:

  • Option C assumes force is directly proportional to \( \omega \), ignoring the square.
  • Option A and Option D are mathematically incorrect for a factor of 3 squared.

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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