Physics Work & Energy MDCAT 2010
PMDC Verified Question 101 of 108
Which one of the following is a non-conservative force?
A
Electric force
B
Gravitational force
C
Elastic spring force
D
Frictional force
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Frictional force
Concept:

A non-conservative force is a force for which the work done depends on the path taken. The mechanical energy of a system is not conserved when non-conservative forces act (it dissipates as heat or sound).

Formula:

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

Solution:

  • Electric, gravitational, and elastic spring forces are all conservative forces because work done by them over a closed loop is zero.


  • Frictional force is path-dependent and dissipates energy as heat, making it a classic non-conservative force.


Why other options are incorrect:

Options A, B, and C are fundamental conservative fields where potential energy can be perfectly defined and recovered.

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