Two train are moving in a straight line in the same direction with a speed of 80 km/h. The relative velocity of one trains w.r.t. each other is

Options

A. 80 km/h
B. 40 km/h
C. Zero
D. 160 km/h

Answer

To solve the problem of finding the relative velocity of one train with respect to the other when both trains are moving in the same direction at the same speed, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the velocities of the trains**:
- Let the speed of Train A (VA) = 80 km/h.
- Let the speed of Train B (VB) = 80 km/h.

2. **Understand the concept of relative velocity**:
- The relative velocity of one object with respect to another is given by the formula:
\[ V_{AB} = V_A - V_B \]
- Here, \(V_{AB}\) is the velocity of Train A with respect to Train B.

3. **Substitute the values into the formula**:
- Using the values we identified:
\[ V_{AB} = 80 \text{ km/h} - 80 \text{ km/h} \]

4. **Calculate the relative velocity**:
- Performing the subtraction:
\[ V_{AB} = 0 \text{ km/h} \]

5. **Interpret the result**:
- A relative velocity of 0 km/h indicates that from the perspective of either train, the other train appears to be at rest. This means that both trains are moving together at the same speed in the same direction.

### Conclusion:
The relative velocity of one train with respect to the other is 0 km/h.