Physics Rotational & Circular Motion MDCAT 2017
PMDC Verified Question 84 of 95
A body is moving in a circular path with constant speed. The magnitude of tangential and centripetal acceleration are:
A
\( \text{Tangential: } rv^2 \quad \text{Centripetal: } 0 \)
B
\( \text{Tangential: } 0 \quad \text{Centripetal: } \frac{v^2}{r} \)
C
\( \text{Tangential: } 0 \quad \text{Centripetal: } 0 \)
D
\( \text{Tangential: } \frac{v^2}{r} \quad \text{Centripetal: } \frac{v^2}{r} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: \( \text{Tangential: } 0 \quad \text{Centripetal: } \frac{v^2}{r} \)
Concept:

In uniform circular motion, speed is constant. Tangential acceleration measures the rate of change of speed, while centripetal acceleration measures the rate of change of direction.

Formula:

$$ a_t = \frac{dv}{dt} \quad \text{and} \quad a_c = \frac{v^2}{r} $$

Solution:

  • Since speed \( v \) is perfectly constant, \( \Delta v = 0 \), meaning tangential acceleration \( a_t = 0 \).
  • Because the body is traveling in a circle, its direction is continuously changing, which is driven by an inward centripetal acceleration of \( a_c = \frac{v^2}{r} \).


Why other options are incorrect:

  • Option C ignores the directional change required for circular motion.
  • Option D wrongly assumes speed is changing.

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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