Physics Work & Energy ETEA 2023
PMDC Verified Question 29 of 108
A 200 N force acts on 8 kg crate that starts from rest. At the instant the object has gone 2m, the rate at which the force is doing work is:
A
2.5 W
B
25 W
C
75 W
D
2000 W
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: 2000 W
Concept:

The "rate at which work is done" is Power. Find the velocity at the 2m mark using kinematics, then use \( P = Fv \).

Formula:

$$ a = \frac{F}{m} \quad ; \quad v_f^2 = v_i^2 + 2ad \quad ; \quad P = F \times v_f $$

Solution:

  • Acceleration: \( a = \frac{200}{8} = 25 \text{ m/s}^2 \).


  • Velocity at 2m: \( v_f^2 = 0 + 2(25)(2) = 100 \).


  • \( v_f = \sqrt{100} = 10 \text{ m/s} \).


  • Instantaneous Power: \( P = 200 \text{ N} \times 10 \text{ m/s} = 2000 \text{ W} \).


Why other options are incorrect:

Option B (25) is merely the acceleration. If you multiply force by displacement you get Work (400 J), but the question asks for the rate (Power).

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