Question

A person accidentally drops her phone off a side balcony of a building. The height of the phone as it drops can be modeled with the equation h= -16t^2+80 where h is measured in feet and t represents the number of seconds since the phone was dropped. How long does it take for the phone to land? Round to the nearest tenth of a second

Answer 1

It takes 2.24 s for the phone to land.

Explanation:

The height of the phone as it drops can be modeled with the equation

h= -16t²+80

where h is measured in feet and t represents the number of seconds since the phone was dropped.

When the phone hits the ground then height of the phone becomes zero.

i.e h=0

-16t²+80=0

⇒16t²=80

`\Rightarrow t^2=(80)/(16)`

⇒ t² =5

`\Rightarrow t=\pm\sqrt 5`

∴t=2.24 s [ since time can not negative]

It takes 2.24 s for the phone to land.