Aball is thrown upward with an initial velocity of 40 feet per second from ground level. the height of the ball, in feet, after t seconds is given by h= -16t^2 + 40t. at the same time, a balloon is rising at a constant rate of 10 feet per second. its height, in feet, after t seconds is given by h = 10t. find the time it takes for the ball and the balloon to reach the same height and explain.