After terminal velocity is reached the acceleration of a body falling through a viscous fluid is:

Options

A. zero
B. equal to g
C. less than g
D. more than g

Explanation

To solve the question, we need to understand the concept of terminal velocity and the forces acting on a body falling through a viscous fluid.

### Step-by-Step Solution:

1. **Understanding Terminal Velocity**:
- Terminal velocity is the constant speed that a freely falling object eventually reaches when the resistance of the medium (in this case, the viscous fluid) prevents further acceleration.

2. **Forces Acting on the Body**:
- When a body is falling through a viscous fluid, three main forces act on it:
- The gravitational force (weight) acting downwards, denoted as \( mg \).
- The buoyant force acting upwards, denoted as \( F_b \).
- The viscous drag force acting upwards, denoted as \( F_v \).

3. **Condition at Terminal Velocity**:
- At terminal velocity, the body stops accelerating. This means that the net force acting on the body is zero. Mathematically, this can be expressed as:
\[ mg = F_b + F_v \]
- Since the net force is zero, the acceleration of the body is also zero.

4. **Conclusion**:
- Therefore, after terminal velocity is reached, the acceleration of the body falling through a viscous fluid is:
\[ \text{Acceleration} = 0 \, \text{m/s}^2 \]

### Final Answer:
The acceleration of a body falling through a viscous fluid after terminal velocity is reached is **0 m/s²**.

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