As a body is projected to a high altitude above the earths surface, the variation of the acceleration of gravity with respect to altitude y must be taken into account. neglecting air resistance, this acceleration is determined from the formula a=− g 0 [ r 2 /(r+y ) 2 ] , where g 0 = 9.81 m/ s 2 is the constant gravitational acceleration at sea level, r = 6356 km is the radius of the earth, and the positive direction is measured upward. with what velocity does the particle strike the earth if it is released from rest at an altitude y0 = 800 km?