Question 14: Work, Energy and Power & Circular Motion

Question

Which one of the following forces cannot be expressed in terms of potential energy?

Accepted Answer

The correct answer is:
$$	extbf{Option A: Frictional force}$$
Here's why:
Conservative vs. Non-Conservative Forces:
Conservative Forces:
These are forces for which the work done is independent of the path taken; they only depend on the initial and final positions. For conservative forces, you can define a potential energy function. Examples include CoulombÃ¢ÂÂs force, gravitational force, and the restoring force of a spring.
Non-Conservative Forces:
These forces depend on the path taken and usually result in energy dissipation (often as heat). Friction is a typical example, and hence, it cannot be described solely by a potential energy function.
Example Explanations:
CoulombÃ¢ÂÂs Force:
It is a conservative force because the work done in moving a charge in an electric field only depends on the difference in electric potential between two points.
Gravitational Force:
It is also conservative. The potential energy associated with gravitational force is given by gravitational potential energy, for example, $$U = mgh$$ near the EarthÃ¢ÂÂs surface.
Restoring Force:
For a spring, the force is given by HookeÃ¢ÂÂs law: $$F = -kx$$ and the corresponding potential energy is $$U = \frac{1}{2}kx^2.$$ This is a conservative force.
Since friction is a non-conservative force that dissipates energy, it cannot be expressed in terms of potential energy.
Therefore, the correct answer is Option A: Frictional force.

Answer

Frictional force

Answer

Coulomb’s force

Answer

Restoring force

Answer

Gravitational force

Work, Energy and Power & Circular Motion

Which one of the following forces cannot be expressed in terms of potential energy?

Choose the correct answer: