An object of mass m is projected away from the surface of the earth in the direction per- pendicular to the surface of the earth with an initial speed vo. assume that there is no air resistance. (a) find an expression for the velocity of the object in terms of its distance x from the surface of the earth during the period when the object is rising. (b) find the least initial speed of the object such that the object does not come back to the earth. this speed is called the escape speed. solution.