Q. The mass of a spaceship is $1000kg$. It is to be launched from the earth’s surface out into free space. The value of $'g'$ and $'R'$ (radius of earth) are $10m/s^{2}$ and $6400km$ respectively
A) $6.4 \times 10^{11}\ Joules$
B) $6.4 \times 10^{8}\ Joules$
C) $6.4 \times 10^{9}\ Joules$
D) $6.4 \times 10^{10}\ Joules$
Explanation
(d) $W = 0 - \left( - \frac{GMm}{R} \right) = \frac{GMm}{R}$
$= gR^{2} \times \frac{m}{R} = mgR$
$= 1000 \times 10 \times 6400 \times 10^{3}$
$= 64 \times 10^{9}J$
$= 6.4 \times 10^{10}J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.