A space-ship entering the earths atmosphere is likely to catch fire, this is due to

Options

A. surface tension of air
B. Air friction
C. greater proportional of `O_(2)` in the atmosphere at higher height
D. high temperature of upper atmopshere

Answer

To solve the question regarding why a spaceship entering the Earth's atmosphere is likely to catch fire, we can break it down step by step:

### Step-by-Step Solution:

1. **Understanding the Scenario**:
- A spaceship re-entering the Earth's atmosphere travels at very high speeds, often several kilometers per second.

**Hint**: Consider the conditions the spaceship faces as it enters the atmosphere.

2. **Identifying Key Factors**:
- As the spaceship enters the atmosphere, it encounters air resistance or friction. This friction occurs because the air molecules collide with the surface of the spaceship.

**Hint**: Think about what happens when an object moves quickly through a fluid (like air).

3. **Effect of High Velocity**:
- The high velocity of the spaceship increases the kinetic energy of the air molecules in front of it, leading to a significant rise in temperature due to compression and friction.

**Hint**: Recall how kinetic energy relates to temperature and energy transfer.

4. **Resulting Heat Generation**:
- The intense friction generates heat, which can raise the temperature of the spaceship's surface to the point where it can ignite materials or cause combustion.

**Hint**: Consider the relationship between heat and combustion.

5. **Conclusion**:
- Therefore, the primary reason a spaceship is likely to catch fire upon re-entry is due to **air friction** caused by its high velocity.

**Hint**: Reflect on the options given in the question and how they relate to the concept of friction and heat.

### Final Answer:
The correct answer is that a spaceship entering the Earth's atmosphere is likely to catch fire due to **air friction**.