ewton's Law of Gravitation states: x"=- GR² x² where g = gravitational constant, R = radius of the Earth, and x = vertical distance travelled. This equation is used to determine the velocity needed to escape the Earth. a) Using chain rule, find the equation for the velocity of the projectile, v with respect to height x. b) Given that at a certain height Xmax, the velocity is v= 0; find an inequality for the escape velocity.