A pilot of a helicopter plans to release a bucket of water on a forest fire. The height y in feet of water t seconds after its release is modeled by y = − 16 t 2 − 2 t + 400 . How long will it take for the water to reach the ground? Round to one number after the decimal point.

Respuesta :

Answer:

4.93 seconds

Step-by-step explanation:

The height y in feet of water t seconds after its release is given by the equation as follows :

[tex]y=-16t^2-2t+400[/tex]

We need to find the taken taken for the water to reach the ground. When it reach the ground, y will be equal to 0. So,

[tex]-16t^2-2t+400=0[/tex]

Above is a quadratic equation whose solutions can be calculated as follows :

[tex]t=\dfrac{-(-2)\pm \sqrt{(-2)^2-4\times (-16)\times 400} }{2\times (-16)}\\\\t=\dfrac{-(-2)+ \sqrt{(-2)^2-4\times (-16)\times 400} }{2\times (-16)}, \dfrac{-(-2)- \sqrt{(-2)^2-4\times (-16)\times 400} }{2\times (-16)}\\\\t=-5.062\ s\ \text{and}\ 4.93\ s[/tex]

Neglecting negative value.

Hence, it will take 4.93 seconds for the water to reach the ground