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Assertion : Let W(1) be the work done in...

Assertion : Let `W_(1)` be the work done in taking away a satellite from the surface of earth to its orbit and then `W_(2)` the work done in rotating the satellite in circular orbit there. Then, `W_(1)=W_(2)`
Reason : `W_(2)=(GMm)/(4R)`

A

If both Assertin and Reason are correct and Reason is the correct explanation of Assertion

B

If both Assertion and Reason are correct but Reason is not the correct explanation of Assertion

C

If Assertion is true but Reason is false

D

If Assertion is false but Reason is true

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The correct Answer is:
To solve the problem, we need to analyze both the assertion and the reason provided. ### Step-by-Step Solution: 1. **Understanding the Assertion**: - The assertion states that the work done in moving a satellite from the surface of the Earth to its orbit (W₁) is equal to the work done in rotating the satellite in its circular orbit (W₂). 2. **Calculating W₁ (Work Done to Move the Satellite)**: - When moving a satellite from the Earth's surface to a height \( h \), the work done can be calculated using the formula: \[ W_1 = mgh \] - However, since the gravitational force changes with height, we need to integrate the force over the distance. The work done against gravity when moving to a height \( h \) is: \[ W_1 = \int_{R}^{R+h} \frac{GMm}{r^2} \, dr \] - Evaluating this integral gives: \[ W_1 = GMm \left( \frac{1}{R} - \frac{1}{R+h} \right) = \frac{GMm h}{R(R+h)} \] 3. **Calculating W₂ (Work Done to Rotate the Satellite)**: - The work done to keep the satellite in circular motion at height \( h \) is related to its kinetic energy. The gravitational force provides the necessary centripetal force for circular motion. - The speed \( v \) of the satellite in orbit is given by: \[ v = \sqrt{\frac{GM}{R+h}} \] - The kinetic energy (which is also the work done to maintain the satellite in orbit) is: \[ W_2 = \frac{1}{2} mv^2 = \frac{1}{2} m \left(\frac{GM}{R+h}\right) = \frac{GMm}{2(R+h)} \] 4. **Comparing W₁ and W₂**: - From our calculations, we have: \[ W_1 = \frac{GMm h}{R(R+h)} \] \[ W_2 = \frac{GMm}{2(R+h)} \] - For \( W_1 \) to equal \( W_2 \), we would need: \[ \frac{GMm h}{R(R+h)} = \frac{GMm}{2(R+h)} \] - This equality does not hold true in general, indicating that the assertion \( W_1 = W_2 \) is false. 5. **Evaluating the Reason**: - The reason states that \( W_2 = \frac{GMm}{4R} \). This is incorrect based on our calculation of \( W_2 \), which is \( \frac{GMm}{2(R+h)} \). ### Conclusion: - The assertion is false, and the reason is also false. Therefore, the statement "if assertion is false but reason is true" is incorrect.

To solve the problem, we need to analyze both the assertion and the reason provided. ### Step-by-Step Solution: 1. **Understanding the Assertion**: - The assertion states that the work done in moving a satellite from the surface of the Earth to its orbit (W₁) is equal to the work done in rotating the satellite in its circular orbit (W₂). 2. **Calculating W₁ (Work Done to Move the Satellite)**: ...
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DC PANDEY ENGLISH-GRAVITATION-(B) Chapter Exercises
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  7. Assertion : Four point masses each of mass m are placed at points 1, 2...

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  8. Assertion : Let W(1) be the work done in taking away a satellite from ...

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  9. Assertion : Two spherical shells have masses m(1) and m(2). Their radi...

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  10. Match the following {:(,"Column-I",,"Column-II"),("(A)","Kepler's fi...

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  11. Density of a planet is two times the density of earth. Radius of this ...

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  12. On the surface of earth acceleration due gravity is g and gravitationa...

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  13. Let V and E denote the gravitational potential and gravitational field...

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  14. Two concentric spherical shells are as shown in figure. Match the foll...

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  15. Match of following columns {:(,"Column-I",,"Column-II"),("(A)",under...

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  16. A particle is projected from the surface of earth with speed v. Suppos...

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  17. In elliptical orbit of a planet, as the planet moves from apogee posit...

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  18. Match the following columns {:(,"Column-I",,"Column-II"),("(A)",unde...

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  19. If earth decreases its rotational speed. Match the following columns ...

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  20. Match the following columns. (for a satellite in circular orbit) {:(...

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