Essential characteristic of equilibrium is:

Options

A. Momentum equals zero
B. Accleration-equals zero
C. K.E. equals zero
D. Velocity equals zero

Explanation

To solve the question regarding the essential characteristics of equilibrium, we will break down the concept step by step.

### Step-by-Step Solution:

1. **Understanding Equilibrium**:
- An object is said to be in equilibrium when the net force acting on it is zero. This means that all the forces acting on the object are balanced.

2. **Net Force**:
- According to Newton's second law of motion, the net force (F_net) acting on an object is given by the equation:
\[ F_{\text{net}} = m \cdot a \]
- Where \( m \) is the mass of the object and \( a \) is its acceleration.

3. **Condition for Equilibrium**:
- For an object to be in equilibrium, the net force must be zero:
\[ F_{\text{net}} = 0 \]
- This leads us to conclude:
\[ m \cdot a = 0 \]

4. **Analyzing the Equation**:
- Since mass \( m \) cannot be zero (as it would imply the object does not exist), the only possibility for the equation to hold true is if the acceleration \( a \) is zero:
\[ a = 0 \]

5. **Conclusion**:
- Therefore, the essential characteristic of equilibrium is that the acceleration of the object is zero, which implies that the object is either at rest or moving with a constant velocity.

### Final Answer:
The essential characteristic of equilibrium is that the net force acting on an object is zero, which results in zero acceleration.

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