Two planets have masses M and 16   M and their radii are a and 2 a , respectively. The separation…

Two planets have masses M and 16 M and their radii are a and 2a, respectively. The separation between the centres of the planets is 10a. A body of mass m is fired from the surface of the larger planet towards the smaller planet along the line joining their centres. For the body to be able to reach at the surface of smaller planet, the minimum firing speed needed is :
  1. 2GMa
  2. 4GMa
  3. GM2ma
  4. 325GMa

Solution

  

12mu2+-G×10Mm2a-GMm8a=0-G×16Mm8a-GM×m2a

u=45GM4a

u=325GMa

Asked in: JEE Main 2020 (06 Sep Shift 2)

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