Question

A football is kicked straight up from a height of 5 feet with an initial speed of 55 feet per second. The formula h equals negative 16 t squared plus 55 t plus 5 describes the​ ball's height above the​ ground, h, in​ feet, t seconds after it was kicked. How long will it take for the football to hit the​ ground?

Answer 1

Answer:

3.53 second

Explanation:

The formula for the height is

$h=-16t^{2}+55t+5$

When it hits the ground, the height is zero.

So, put h = 0 in the above equation

$0=-16t^{2}+55t+5$

$16t^{2}-55t-5=0$

$t=\frac{+55\pm \sqrt{55^{2}+4\times 5\times 16}}{2\times 16}$

$t=\frac{+55\pm 57.84}{2\times 16}$

Take positive sign

t = 3.53 second.

Thus, the time taken to hit the ground is 3.53 second.