A body is thrown vertically upwards from the surface of earth in such a way that it reaches upto a height equal to 10 Re. The velocity (in km/s) imparted to the body will be

Work done in going from a distance r1 to a distance r2 away from centre ​ of the earth, by a body of mass m, isW=GMm(1/r1−1/r2)​ For our case we should have ​1/2mv2=GMm[(1/Re)−(1/11Re)]​=(GMm/Re)×(10/11)​⇒v=2GM10Re11=1011×11.2 km/s=10.68 km/s