A man runs along a horizontal road on a rainy day. His umbrella vertical in order to protect himself from the rain then rain actually 

Options

A. coming from front actually
B. coming from back to a man
C. falling vertically
D. either of 1,2 or 3

Answer

To solve the problem of determining the direction from which the rain is falling when a man runs with his umbrella held vertically, we can analyze the situation step by step.

### Step 1: Understand the Scenario
The man is running along a horizontal road, and he holds his umbrella vertically to shield himself from the rain. We need to determine the direction of the rain relative to the man's motion.

### Step 2: Analyze the Motion
When the man runs, he creates a horizontal velocity. If the rain is falling vertically, the man would feel the rain hitting him directly from above. If the rain is falling at an angle, the man must adjust the angle of his umbrella to stay dry.

### Step 3: Consider the Direction of Rain
1. **Rain Falling from the Front**: If the rain is falling from the front, it will have both a vertical component (downward) and a horizontal component (toward the man). As the man runs, he would feel the rain hitting him at an angle, and he would need to tilt his umbrella backward to stay dry. Therefore, this scenario does not allow him to hold the umbrella vertically.

2. **Rain Falling from the Back**: If the rain is falling from behind the man, it will again have a vertical component and a horizontal component (toward the front). In this case, as the man runs forward, he would not feel the rain hitting him from the front, and he can hold his umbrella vertically without getting wet. This scenario allows him to stay dry.

3. **Rain Falling Vertically**: If the rain is falling vertically, the man would feel the rain directly above him, and he would need to hold his umbrella vertically to protect himself.

### Step 4: Conclusion
From the analysis, we conclude that the only situation where the man can run with his umbrella held vertically and still be protected from the rain is when the rain is falling from behind him. Thus, the correct answer is that the rain is falling from the back.

### Final Answer
The rain is falling from behind the man.

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