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JEE Main 2016 · Escape Velocity

Escape Velocity question from JEE Main 2016

Q68JEE Main 2016Medium

Escape Velocity

A satellite is revolving in a circular orbit at a height ′h′'h' from the earth's surface (radius of earth R; h<<RR;\ h << R). The minimum increase in its orbital velocity required, so that the satellite could escape from the earth's gravitational field, is close to: (Neglect the effect of atmosphere.)

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Answer: (d)

  1. For h≪Rh \ll R: vo=gRv_o = \sqrt{gR} and ve=2gRv_e = \sqrt{2gR} at that point.
  2. Minimum increase =2gR−gR=gR(2−1)= \sqrt{2gR} - \sqrt{gR} = \sqrt{gR}(\sqrt{2}-1).
  3. So the answer is (d) gR(2−1)\sqrt{gR}(\sqrt{2}-1).
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