This section contains Assertion and Reason type questions. Each question has 4 choices (1), (2), (3) and (4), out of which only one is correct.
Assertion (A) A planet moves faster, when it is closer to the sun in its orbit and vice versa.
Reason (R) Orbital velocity in the orbit of planet is constant.

Options

A. If both Assertion and Reason are true and the Reason Is the correct explanation of the Assertion,
B. If both Assertion and Reason are true but Reason Is not the correct explanation of the Assertion.
C. If Assertion Is correct but Reason Is Incorrect.
D. lf Assertion Is Incorrect but Reason Is correct.

Answer

To solve the assertion and reason type question, we will analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states: "A planet moves faster when it is closer to the sun in its orbit and vice versa."
- This is based on Kepler's laws of planetary motion, specifically the law of areas, which states that a line segment joining a planet and the sun sweeps out equal areas during equal intervals of time. This implies that when a planet is closer to the sun, it must travel a greater distance in the same amount of time, hence it moves faster.

2. **Understanding the Reason**:
- The reason states: "Orbital velocity in the orbit of a planet is constant."
- This statement is not true for elliptical orbits. In a circular orbit, the orbital velocity can be constant, but for elliptical orbits (which most planets follow), the speed varies depending on the distance from the sun. When the planet is closer to the sun, it moves faster, and when it is farther away, it moves slower.

3. **Evaluating the Statements**:
- The assertion is correct because it aligns with the principles of orbital mechanics.
- The reason is incorrect because it inaccurately describes the nature of orbital velocity in elliptical orbits.

4. **Conclusion**:
- Since the assertion is true and the reason is false, we can conclude that the correct choice is option (3): "Assertion is correct, but reason is incorrect."

### Final Answer:
The correct option is (3): Assertion is correct, but reason is incorrect.

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