A rocket is launched normal to the surface of the Earth, away from the Sun, along the line joining the Sun…

A rocket is launched normal to the surface of the Earth, away from the Sun, along the line joining the Sun and the Earth. The Sun is 3×105 times heavier than the Earth and is at a distance 2.5×104  times larger than the radius of the Earth. The escape velocity from Earth's gravitational field is ve=11.2 km s-1 . The minimum initial velocity vs required for the rocket to be able to leave the Sun-Earth system is closest to
(Ignore the rotation and revolution of the Earth and the presence of any other planet)
  1. vs=22 km s-1
  2. vs=72 km s-1
  3. vs=42 km s-1
  4. vs=62 km s-1

Solution

Given ve=11.2km/sec= 2GMeRe

12mvs2-GMsmr-GMemRe=0-0      where r = distance of rocket from Sun

    vs= 2GMeRe+2GMsr

Given  Ms=3×105 Me  and  r=2.5×104Re

  vs= 2GMeRe+2G3×105Me2.5×104Re

= 2GMeRe 1+3×1052.5×104

= 2GMeRe×13

   vs=42km/s

Asked in: JEE Advanced 2017 (Paper 2)

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