Question

Which of the following is/are correct about conservative and non-conservative forces?
(A) For conservative and non-conservative forces conservation of energy holds good.
(B) Friction is a conservative force.
(C) The work done by a conservative force in a closed path is zero.
(D) Friction is a non-conservative force.
Choose the correct answer from the options given below:

• A. (A), (C) and (D) only
• B. (A), (B) and (C) only
• C. (A), (B) and (D) only
• D. (B), (C) and (D) only

Hint:

Key distinctions to remember:
{Conservative Force}: Work is path-independent; work in a closed loop is zero; mechanical energy is conserved. Examples: Gravity, electrostatic force, ideal spring force.
{Non-Conservative Force}: Work is path-dependent; work in a closed loop is not zero; mechanical energy is dissipated. Examples: Friction, air resistance, viscous drag.
The Law of Conservation of *Total* Energy always holds.

Answer 1

The Correct Option is A

Step 1: Concept Identification:
This question assesses understanding of the definitions and properties of conservative and non-conservative forces in physics.
Step 2: Statement Analysis:
Examination of each statement follows:

(A) Conservation of energy is valid for both conservative and non-conservative forces. This statement is accurate. The law of conservation of total energy is a universal principle. Mechanical energy (Kinetic + Potential) is conserved under conservative forces. For non-conservative forces, mechanical energy is not conserved but transforms into other energy forms (e.g., heat from friction). Total energy in an isolated system remains constant irrespective of internal forces.

(B) Friction is a conservative force. This statement is false. Friction is a prime example of a non-conservative force. The work done by friction is path-dependent and dissipates mechanical energy.

(C) The work done by a conservative force over a closed path is zero. This is a fundamental characteristic of a conservative force. When a particle traverses a closed loop and returns to its origin, the net work performed by a conservative force (such as gravity or an ideal spring force) is null.

(D) Friction is a non-conservative force. This statement is true. As detailed for statement (B), friction is a dissipative, path-dependent force, thus it is non-conservative.
Step 3: Conclusion:
Statements (A), (C), and (D) are correct. Statement (B) is incorrect. Consequently, the correct selection comprises (A), (C), and (D).