Q64 / 90 · JEE Main 2023 (08 Apr Shift 2) · Physics

The orbital angular momentum of a satellite is L, when it is revolving in a circular orbit at height h from earth surface. If the distance of satellite from the earth centre is increased by eight times to its initial value, then the new angular momentum will be

  • A
    8 L
  • B
    9 L
  • C
    4 L
  • Correct answer
    D
    3 L

Solution

For a satellite revolving around the Earth in a circular orbit, it can be written that

mv2r=GMmr2   ...1 (r=R+h is the distance from the centre of the Earth)

Simplify equation (1) to obtain the linear speed of the satellite.

v=GMr

Thus, the angular momentum of the satellite is given by

L=mvr=mrGMr=mGMr   ...2

Similarly, for distance r' from the centre of the Earth, the angular momentum is given by

L'=mGMr'   ...3

Divide equation (3) by equation (2) to obtain the required angular momentum.

L'L=mGMr'mGMr= r'r   ...4

Now, r'=r+8r=9r

Substitute the known values of the parameters into equation (4) to obtain the required angular momentum.

L'L=9⇒L'=3L

Hence, the correct answer is option: 'D'.

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