Question

If a football player passes a football from 4 feet off the ground with an initial velocity of 36 feet per second, how long will it take the football to hit the ground? Use the equation h = −16t2 + 6t + 4. Round your answer to the nearest hundredth.

0.72
0.65
0.35
0.27

Answer 1

0.72

Explanation:

I took the quiz

Answer 2

Given:

The height of ball is represented by the equation is

`h=-16t^2+6t+4`

To find:

The time taken by ball to hit the ground.

Solution:

First we need to find the zeroes of the given equation. So, for zeroes h=0.

`-16t^2+6t+4=0`

Here,
`a=-16,b=6,c=4`. Usingquadratic formula, we get

`t=(-b\pm √(b^2-4ac))/(2a)`

`t=(-6\pm √(6^2-4(-16)(4)))/(2(-16))`

`t=(-6\pm √(36+256))/(-32)`

`t=(-6\pm √(292))/(-32)`

`t=-(-6+ 17.088)/(-32),(-6+ 17.088)/(-32)`

`t=0.7215,-0.3465`

Time cannon be negative. So, at t=0.7215 the ball will hit the ground. Time taken by ball to hit the ground is

`t=0.7215-0`

`t=0.7215`

Round your answer to the nearest hundredth.

`t\approx 0.72`

So, the ball will hit the ground after 0.72 seconds.

Therefore, the correct option is A.