Question

(a) Explain the mathematical equation to calculate orbital velocity of a satellite. Write the meanings of the symbols used.
(b) Explain how a protostar is formed.

Answer 1

a)The orbital velocity of a satellite is obtained by the balance between the gravitational force on the satellite and the centrifugal force on the satellite.
So if the satellite of mass m is moving around earth or any other planet of mass $M$ at distance $R$ from center with orbital velocity $v$ then
Gravitational force $\frac{GMm}{R^2}$ and centrifugal force $\frac{m{v}^2}{R}$
$$\frac{GMm}{R^2}=\frac{m{v}^2}{R}$$
$$v=\sqrt{\frac{GM}{R}}$$
b) Protostar is a hypothetical cloud of dust and atoms in space believed to develop into a star. A protostar is formed about a million years after a gas clump from an interstellar gas cloud has started to rotate and form a disk. It is a large object that forms by contraction out of the gas of a giant molecular cloud in the interstellar medium. The protostar is simply the core of the disk that formed from the clump of gas that was compressed inside the gas cloud.The protostar phase is an early stage in the process of star formation.