Physics Work & Energy PMDC 2020
PMDC Verified Question 77 of 108
Which of the following force is non-conservative force?
A
Frictional force
B
Gravitation force
C
Electric force
D
Elastic spring force
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Frictional force
Concept:

A non-conservative force dissipates mechanical energy (often into heat) and the work done by it depends entirely on the path taken, not just initial and final positions.

Formula:

$$ W_{\text{closed}} \neq 0 $$

Solution:

  • Frictional force opposes motion constantly. If you move an object in a closed loop, friction does negative work the entire time, dissipating energy.


  • Therefore, friction is path-dependent and non-conservative.


Why other options are incorrect:

Gravitational, electric, and spring forces are conservative. Energy stored against them can be perfectly recovered as kinetic energy.

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