Physics Rotational & Circular Motion UHS 2024
PMDC Verified Question 13 of 95
A roller coaster is moving with \( 30 \text{ ms}^{-1} \) on a circular track of radius \( 30 \text{ m} \), then net mass of coaster + passengers is 'm' the centripetal force acting on it is:
A
\( 900 \text{ m} \)
B
\( m \)
C
\( 450 \text{ m} \)
D
\( 30 \text{ m} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: \( 30 \text{ m} \)
Concept:

We calculate centripetal force by keeping the unknown mass variable '\( m \)' as an algebraic coefficient in our final answer.

Formula:

$$ F_c = \frac{mv^2}{r} $$

Solution:

  • Given velocity \( v = 30 \text{ m/s} \).
  • Given radius \( r = 30 \text{ m} \).
  • Substitute into the formula: \( F_c = \frac{m(30)^2}{30} \).
  • The square on the top cancels out the 30 on the bottom.
  • \( F_c = m(30) \), which is typically written algebraically as \( 30m \).


Why other options are incorrect:

  • Option A occurs if you square the 30 but forget to divide by the radius.
  • Option B occurs if you assume velocity and radius cancel completely without squaring.

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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