Question

Explorer $38$, a radio-astronomy satellite of mass $200$kg, circle the Earth in an orbit of average radius $\frac{3R}{2}$ where $R$ is the radius of the Earth. Assuming the gravitational pull on a mass of $1$kg at the earth's surface to be $10N$, calculate the pull on the satellite

• A. $889N$
• B. $89N$
• C. $8889N$
• D. $8.9N$

Answer 1

The correct option is A $889N$

$g_h=g(1-\frac{2h}{R})=\frac{4g}{h}(sinceh=R+\frac{3R}{2})$
Force on the satellite $=m{g}_h=\frac{4}{9}mg$
$=\frac{4}{9}\times 200\times 10=889N$