A satellite is orbiting the earth in an orbit with a velocity `4 km//s`, then the acceleration due to gravity at that height is (in `ms^(-2)`)

A satellite is revolving round the earth in a circular orbit with a velocity of 8km/s. at a height where acceleration due to gravity is 8m//s^(2) . How high is the satellite from the earth ? (Take R = 6000 km)