In a lake, a fish rising vertically to the surface of water uniformly at the rate of 3 m/s, observes a bird diving vertically towards the water at the rate of 9 m/s. The actual velocity of the dive of the bird is (given, refractive index of water = 4/3)

Options

A. 3.6 m/s
B. 4.5 m/s
C. 6.0 m/s
D. 12.0 m/s

Explanation

To solve the problem, we need to find the actual velocity of the bird diving into the water, given the observed velocity by the fish and the refractive index of water.

### Step-by-Step Solution:

1. **Identify Given Values:**
- Velocity of the fish rising (v_f) = 3 m/s (upward)
- Observed velocity of the bird diving (v_b') = 9 m/s (downward)
- Refractive index of water (μ) = 4/3
...