Which of the following forces is called a conservative force?

Options

A. Frictional force
B. Air resistance
C. Electrostatic force
D. Viscous force

Answer

To determine which of the following forces is a conservative force, we first need to understand the definition of conservative forces.

### Step-by-Step Solution:

1. **Definition of Conservative Force**: A conservative force is defined as a force for which the work done in moving an object between two points is independent of the path taken. This means that the work done only depends on the initial and final positions of the object.

2. **Examples of Conservative Forces**: Common examples of conservative forces include gravitational force and electrostatic force. For instance, when moving an object in a gravitational field, the work done only depends on the height difference, not the path taken.

3. **Non-Conservative Forces**: In contrast, non-conservative forces, such as frictional forces and air resistance, depend on the path taken. For example, the work done against friction will vary based on the distance traveled and the nature of the path.

4. **Analyzing Different Forces**:
- **Frictional Force**: This is a non-conservative force because the work done depends on the path taken.
- **Air Resistance**: This is also a non-conservative force as it varies with the distance and speed of the object.
- **Electrostatic Force**: This is a conservative force because the work done in moving a charge in an electric field only depends on the initial and final positions of the charge, regardless of the path taken.

5. **Conclusion**: Among the forces discussed, the electrostatic force is the one that qualifies as a conservative force.

### Final Answer:
The electrostatic force is called a conservative force.