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A : Work done by the gravitational fo...

A : Work done by the gravitational force is positive when the two point masses are brought from infinity to any two points in space .
R : Gravitational potential energy increases during the above process .

A

If both Assertion & Reason are true . And the reason is the correct explanation of the assertion , then mark (1)

B

If both Assertion & Reason are true but the reason is not the correct explanation of the assertion , then mark (2)

C

If Assertion is true statement but Reason is false , then mark (3)

D

If both Assertion and Reason are false statement , then mark (4)

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question, we need to analyze both the Assertion (A) and the Reason (R) provided. ### Step-by-Step Solution: 1. **Understanding the Assertion (A)**: - The assertion states that the work done by the gravitational force is positive when two point masses are brought from infinity to any two points in space. - When two masses are brought from infinity (where gravitational potential energy is considered zero) to a point in space, the gravitational force does work on the masses. 2. **Calculating Work Done by Gravitational Force**: - The work done \( W \) by the gravitational force can be expressed as: \[ W = U_{\text{initial}} - U_{\text{final}} \] - At infinity, the gravitational potential energy \( U_{\text{initial}} = 0 \). - When the masses are at a distance \( r \), the gravitational potential energy \( U_{\text{final}} \) is given by: \[ U_{\text{final}} = -\frac{G m_1 m_2}{r} \] - Therefore, the work done by the gravitational force becomes: \[ W = 0 - \left(-\frac{G m_1 m_2}{r}\right) = \frac{G m_1 m_2}{r} \] - Since \( G, m_1, m_2, \) and \( r \) are all positive quantities, \( W \) is positive. 3. **Understanding the Reason (R)**: - The reason states that gravitational potential energy increases during the process. - However, as we have established, when moving from infinity to a point in space, the potential energy decreases from zero to a negative value. - Thus, the statement that gravitational potential energy increases is incorrect. 4. **Conclusion**: - The assertion (A) is correct because the work done by the gravitational force is indeed positive. - The reason (R) is incorrect because the gravitational potential energy decreases, not increases. ### Final Answer: - The assertion is correct, but the reason is incorrect. Therefore, the correct option is that Assertion (A) is true and Reason (R) is false. ---
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