Question

Two satellites of earth, $S_1$ and $S_2$, are moving in
the same orbit. The mass of $S_1$ is four times the
mass of $S_2$. Which one of the following statements is true ?

• A. The kinetic energies of the two satellites are
  equal
• B. The time period of $S_1$ is four times that of $S_2$
• C. The potential energies of earth and satellite in
  the two cases are equal
• D. $S_1$ and $S_2$ are moving with the same speed

Answer 1

The correct option is D $S_1$ and $S_2$ are moving with the same speed

$K.E.=\frac{GMm}{2r}\Rightarrow Kineticenergiesareunequal$
$T=\frac{2\pi r^{3/2}}{\sqrt{GM}}\Rightarrow Timeperiodareequal$
$P.E.=-\frac{GMm}{r}\Rightarrow Potentialenergiesareunequal$
$V=\sqrt{\frac{GM}{r}}\Rightarrow Orbitalspeedsareequal$