Question

Two satellites $P$ and $Q$ are in the same circular orbit round the earth. The mass of $P$ is greater than that of $Q$. It follows that

• A. The speed of $P$ is equal to that of $Q$
• B. The speed of $P$ is greater than that of $Q$
• C. The speed of $P$ is less than that of $Q$
• D. The kinetic energy of $P$ is equal to that of $Q$

Answer 1

Answer: (A)

The speed of $P$ is equal to that of $Q$

As the satellites are in a circular orbit, we can write:

$mg=m\frac{v^2}{r}$

or, $v=\sqrt{rg}$

So, we can see that speed of the satellite is independent of mass. So, if the satellites are in same orbit, they will have same speed.