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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 the earth) is 10 m/s2 and 6400 km respectively. The required energy for this work will be

(a) 6.4 x 1010 Joules

(b) 6.4 x 1011 Joules

(c) 6.4 x 10Joules

(d) 6.4 x 10Joules

in Physics | 21 views

+1 vote

The correct answer is option (a) 6.4 x 1010 Joules

Explaination ::

The energy required is given by = $$GMm\over R$$

=$$gR^2 \times{ m\over R} (∵ g = {GM\over R2})$$= mgR

= 1000 x 10 x 6400 x 103

= 64 x 109 J

= 6.4 x 1010 J

by Expert (10.9k points)