+0

# Algebra

0
68
2

At time t=0, a ball is thrown downward at 24 feet per second from a height of $$180$$ feet above the ground. The equation $h = -16t^2 - 24t +180$ describes the height (in feet) of the ball. In how many seconds will the ball hit the ground? Express your answer as a decimal.

Feb 6, 2022

#1
0

The answer is t = 3.6.

Feb 6, 2022
#2
+36416
+1

When the ball hits the ground  ,  h = 0

=  -16t^2 - 24 t + 180

Use Quadratic Formula with  a = -16    b  = -24    c = 180

$$t = {-(-24) \pm \sqrt{(-24)^2-4(-16)(180)} \over 2(-16)}$$

to calculate 't'    (Hint: it is NOT 3.6 sec )   ==== throw out the negative 't' value

Feb 7, 2022