SOLUTION: Lewis Tower in Philadelphia is 400 ft. high. Suppose that a ball is projected upward from the top of the tower, and its position in feet above the ground is given by the quadratic
Question 369002: Lewis Tower in Philadelphia is 400 ft. high. Suppose that a ball is projected upward from the top of the tower, and its position in feet above the ground is given by the quadratic function defined by f(t)= -16t^2+45t+400, where t is the number of seconds elapsed. How long to the nearest 10th of a second will it take for the ball to reach a height of 200 ft. above the ground?
I used the pythagorean theorem but I got 6.6 and the answer is 5.2. I don't know what I am doing wrong. Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!
Hi,
position in feet above the ground = -16t^2+45t+400
How long will it take for the ball to reach a height of 200 ft. above the ground
200 = -16t^2+45t+400
16t^2 - 45t - 200 = 0 Note: solution t < 0 cannot use
t = 166.8 /32 = 5.2 sec