Work done by a non - conservative force

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Question

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BPSC AE Paper 4 (General Engineering Science) 10 Nov 2022 Official Paper

acting on a particle would be zero, if the moving particle comes back to its original starting position
is always positive
would be negative, will lead to loss in energy
is independent of the path followed by the particle it acts upon

Answer 1

Concept:

Non-Conservative Force:

A non-conservative force is a force for which the work done depends on the path taken by the object, not just on the starting and ending points. Common examples of non-conservative forces include friction, air resistance, and applied forces.
In contrast to conservative forces (like gravitational force and electrostatic force), non-conservative forces dissipate energy, often converting it into heat or other forms of energy.

Characteristics of Work Done by Non-Conservative Forces:

Path Dependence: The work done by a non-conservative force is dependent on the path taken by the particle. If the path changes, the work done will also change, making non-conservative forces path-dependent.
Energy Dissipation: Non-conservative forces usually result in energy dissipation, meaning they convert mechanical energy into other forms like heat, sound, etc. This can lead to a decrease in the mechanical energy of the system.
Non-Zero Net Work in Closed Paths: When a particle moves in a closed path under the action of a non-conservative force, the net work done by that force is not zero. This is because energy is lost due to dissipation (e.g., friction).