A person is sitting in a travelling train and facing the engine. He tosses up a coin and the coin falls behind him. It can be concluded that the train is

Options

A. Moving forward and gaining speed
B. Moving forward and losing speed
C. Moving forward with uniform speed
D. Moving backward with uniform speed

Answer

To solve the problem, we need to analyze the situation described: a person sitting in a moving train tosses a coin upwards, and the coin falls behind him.

### Step-by-Step Solution:

1. **Understanding the Initial Conditions**:
- The person is sitting in a train that is moving forward (towards the engine).
- When he tosses the coin, he gives it an initial upward velocity.

2. **Observing the Coin's Motion**:
- The coin, once tossed, has two components of motion: vertical (upward) and horizontal (forward).
- The horizontal motion of the coin is influenced by the motion of the train.

3. **Analyzing the Coin's Fall**:
- If the train were moving at a constant speed, the coin would maintain the same horizontal velocity as the train when tossed.
- However, since the coin falls behind the person, it indicates that the train is accelerating.

4. **Conclusion About the Train's Motion**:
- If the coin falls behind the person, it means that while the coin is in the air, the train has gained speed and moved ahead of where the coin was initially tossed.
- Therefore, we can conclude that the train is **accelerating forward**.

### Final Conclusion:
The train is moving forward and gaining speed.

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