Earth completes one rotation in

Options

A. 24 hours
B. 24 hour 2 min. and `4.15`sec.
C. `23` hour `56` min. `4.1` sec
D. `23` hour `59` min. and `24` sec.

Answer

**Step-by-Step Solution:**

1. **Understanding Earth's Rotation**: The Earth rotates on its axis, and this rotation defines the length of a day. However, there are two different ways to measure a day: the solar day and the sidereal day.

2. **Defining Solar Day vs. Sidereal Day**:
- A **solar day** is the time it takes for the Earth to rotate once relative to the Sun, which is approximately 24 hours.
- A **sidereal day** is the time it takes for the Earth to rotate once relative to distant stars, which is about 23 hours, 56 minutes, and 4.1 seconds.

3. **Analyzing the Options**:
- **Option A**: 24 hours - This is the duration of a solar day, not the sidereal day.
- **Option B**: 24 hours, 2 minutes, and 4.15 seconds - This is more than 24 hours and is incorrect.
- **Option C**: 23 hours, 56 minutes, and 4.1 seconds - This matches the duration of a sidereal day, making it the correct answer.
- **Option D**: 23 hours, 59 minutes, and 24 seconds - This is also incorrect as it does not match the sidereal day duration.

4. **Conclusion**: The correct answer to the question "Earth completes one rotation in" is **C: 23 hours, 56 minutes, and 4.1 seconds**.

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