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Motion In Straight Line

Question
CBSEENPH11020306

The mass of a spaceship is 1000 kg. It is to be launched from the earth's surface out into free space. The value of 'g'and 'R'(radius of earth) are 10 m/s2 and 6400km respectively. The required energy for this work will be;

  • 6.4 x1011 J

  • 6.4 x108 J

  • 6.4 x109 J

  • 6.4 x109 J

Solution

D.

6.4 x109 J

Potential energy on the earth's surface is -mgR while in free space, it is zero. So, to free the spaceship minimum required energy is
E =mgR
 = 103 x 10 x 6400 x 103 J
 = 6.4 x 1010 J