Assertion : An external force is required to keep a body in motion.
Reason : If the net external force is zero, a body at rest continues to remain at rest and a body in motion continues to move with a uniform velocity.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true and reason is the not correct explanation of assertion.
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Answer

To analyze the assertion and reason provided in the question, we will break down each statement step by step.

### Step 1: Understanding the Assertion
- **Assertion**: "An external force is required to keep a body in motion."
- This statement implies that for a body to maintain its motion, an external force must be applied. However, this is not entirely accurate. According to Newton's first law of motion, a body in motion will continue in motion unless acted upon by an external force. Therefore, the assertion is misleading because a body in motion does not require a continuous external force to keep moving; it will keep moving at a constant velocity unless acted upon by an external force (like friction).

### Step 2: Understanding the Reason
- **Reason**: "If the net external force is zero, a body at rest continues to remain at rest and a body in motion continues to move with a uniform velocity."
- This statement is a correct representation of Newton's first law of motion. It states that if no net external force acts on a body, the body will either remain at rest or continue to move at a constant velocity. This means that the reason correctly explains the behavior of bodies under the influence of forces.

### Step 3: Evaluating the Relationship Between Assertion and Reason
- The assertion states that an external force is required to keep a body in motion, which is not true in the context of Newton's first law. The reason correctly describes the law but does not provide a valid explanation for the assertion. Thus, while both statements may be true in isolation, the reason does not justify the assertion.

### Conclusion
- The assertion is incorrect, while the reason is correct but does not explain the assertion. Therefore, the correct answer is that the assertion is false, and the reason is true, but the reason is not a correct explanation of the assertion.

### Final Answer
- The assertion is false, and the reason is true, but the reason is not a correct explanation of the assertion.

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