The orbital speed for an earth satellite near the surface of the earth is `7km//sec`. If the radius of the orbit is `4` times the radius of the earth, the orbital speed would be

Options

A. 3.5 km/s
B. 7 km/s
C. 72 km/s
D. 14 km/s

Answer

a

Explanation

Orbital velocity `=sqrt((GM)/(R))=7"km/s"`
`v=sqrt((GM)/(4R))" "therefore(7)/(v)=(sqrt(GM//R))/(sqrt(GM//4R))=(2)/(1)`
`therefore" "v=(7)/(2)=3.5"km/s"`