Physics Work & Energy UHS 2022
PMDC Verified Question 40 of 108
Ignoring details associated with friction, extra forces exerted by arm and leg muscles, and other factors, we can consider a pole vault as the conversion of an athlete's running kinetic energy to gravitational potential energy. If an athlete is to lift his body 5m during a vault, what speed must he have when he plants his pole?
A
5 \( \text{ms}^{-1} \)
B
10 \( \text{ms}^{-1} \)
C
15 \( \text{ms}^{-1} \)
D
20 \( \text{ms}^{-1} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: 10 \( \text{ms}^{-1} \)
Concept:

Using the Law of Conservation of Energy, the initial horizontal kinetic energy is entirely converted into vertical gravitational potential energy at the peak of the vault.

Formula:

$$ \frac{1}{2}mv^2 = mgh $$

Solution:

  • The mass \( m \) cancels out on both sides: \( \frac{1}{2}v^2 = gh \).


  • Rearrange for velocity: \( v = \sqrt{2gh} \).


  • Height (\( h \)) = 5 m. Assume standard gravity \( g = 10 \text{ m/s}^2 \).


  • \( v = \sqrt{2 \times 10 \times 5} = \sqrt{100} \).


  • \( v = 10 \text{ m/s} \).


Why other options are incorrect:

Failing to multiply by 2 gives \( \sqrt{50} \approx 7 \). Assuming \( v = gh \) directly gives 50. Only 10 is mathematically sound.

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.

Previous Question All Work & Energy MCQs Next Question

Want to solve full-length papers under timed exam conditions?

Practice with zero-scroll lockdown sprints, dynamic latency zone timers, live peer selection telemetry, and the automated Amber mistake recovery loop.

Enter Arena Sprint iOS App Android App