Question

What is the distance of the spaceship from the earth

Answer 1

Gravitational force on spaceship is given by equation

$F = \frac{Gm_1m_2}{r^2}$

here $m_1, m_2$ = masses of two objects

r = distance between their centers

now it is given that gravitation force due to earth is two times the force of gravitation due to moon

$F_{earth} =2 F_{moon}$

$\frac{GM_e m}{r^2} =2 \frac{GM_m m}{(d-r)^2}$

$\frac{M_e}{r^2} =2 \frac{M_m }{(d-r)^2}$

$M_e (d -r)^2 =2 M_m r^2$

$(\sqrt{2\frac{M_m}{M_e}} + 1)r = d$

given that

$M_m = 7.35 * 10^{22} kg$

$M_e = 5.98 * 10^{24} kg$

d = 384000 km

now from above equation

$(\sqrt{2\frac{7.35* 10^{22}}{5.98*10^{24}}} + 1)r = 384000 km$

r = 269875.5 km

so the distance from earth will be 269875.5 km