Which law of Newton is called the law of equilibrium?

Options

A. Newton's first law of motion
B. Newton's second law of motion
C. Newton's third law of motion
D. Newton's law of gravitation

Answer

To determine which law of Newton is referred to as the law of equilibrium, we can analyze each of Newton's three laws of motion and their implications regarding equilibrium.

### Step-by-Step Solution:

1. **Understanding Equilibrium**:
- Equilibrium refers to a state where the net force acting on an object is zero. This means that the object is either at rest or moving with a constant velocity.

2. **Newton's First Law of Motion**:
- Newton's First Law states that an object at rest will remain at rest, and an object in motion will continue to move at a constant velocity unless acted upon by a net external force. This law implies that if no net force is acting on an object, it is in equilibrium.

3. **Newton's Second Law of Motion**:
- The Second Law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F = ma). This law describes how forces cause changes in motion and does not describe a state of equilibrium.

4. **Newton's Third Law of Motion**:
- The Third Law states that for every action, there is an equal and opposite reaction. This law deals with forces between two bodies but does not define a state of equilibrium.

5. **Conclusion**:
- Since the First Law of Motion describes a condition where the net force is zero and the object remains in its state (either at rest or moving uniformly), it is referred to as the law of equilibrium.

### Final Answer:
The law of equilibrium is Newton's First Law of Motion.

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