# Which of the following forces is non-conservative in nature?

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Which of the following forces is non-conservative in nature?
1. Coulomb
2. Gravitational
3. Plastic
4. Friction

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Correct Answer - Option 4 : Friction

Concept:

• Mechanical Energy: The sum of potential energy and kinetic energy is called mechanical energy.
• Conservative Force: The force under whose influence the mechanical energy remains conserved is called conservative force.

Example: - Gravitational force is a conservative force. An object at height h of mass m is falling under the influence of gravity. Its potential energy at this height  is given as

P = mgh

g is the acceleration due to gravity.

At any point at height x during its motion, the sum of potential energy and kinetic energy will remain the same and equal to h

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

• Conservative Force is path-indedependent. The gain in potential energy depends upon the initial and final position and not upon the path taken.
• Non-Conservative Force: The force under whose influence the mechanical energy does not remain conserved, and some energy is lost in form of heat or sound is called non - conservative force.
• Frictional force, viscous force, air resistance are some of the examples of non-conservative forces.

Explanation:

When the body is under frictional force, it depends upon the coefficient of friction or we can say on the type of surface.

So, if we taken different surfaces to reach from one point to another, the frictional forces will be different.

So, friction is the force that is non - conservative in nature.