The raindrops are hitting the back of a man walking at a speed of `5km//hr`. If he now starts running in the same direction with a constant acceleration, the magnitude of the velocity of the rain with respect to him will

Options

A. gradually increase
B. gradually decrease
C. first decrease then increase
D. first increase then decrease

Explanation

To solve the problem, we need to analyze the situation involving the man and the rain. Here are the steps to find the magnitude of the velocity of the rain with respect to the man as he starts running in the same direction:

### Step 1: Understand the initial conditions
The man is initially walking at a speed of \( V_m = 5 \, \text{km/hr} \) in the same direction as the rain is falling. The rain is hitting him from behind, which means the velocity of the rain \( V_r \) must be greater than \( V_m \).

### Step 2: Establish the relative velocity
The relative velocity of the rain with respect to the man when he is walking can be expressed as:
\[
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