The equation y = -16t^2 + 28t + 180 describes the height (in feet) of a ball tossed up in the air at 28 feet per second from a height of 180 feet from the ground. In how many seconds will the ball hit the ground?
When the ball hits the ground, y = 0
so use the quadratic formula to solve
0 = -16t^2 + 28t + 180 ( toss out the negaative 't' value)