word problem help

[flew62999]

Please help...where do I begin?

A model rocket will be launched from a hill 80 feet above the sea level. The launch site is next to the ocean (sea level), and the rocket will fall into the ocean. The rocket’s distance, s, above sea level at any time, t, is found by the equation s(t)=-16t^2 + 64t + 80. Find the time it takes for the rocket to strike the ocean.

 

[dagr8est]

When the rocket strikes the ocean, the distance above sea level, s(t), is 0.

s(t) = -16t^2+64t+80
0 = -16t^2+64t+80

Solve it using the quadratic equation. You should get -1 or 5, but time cannot be negative so 5 is the answer. Do they give you a unit for time, seconds, minutes, hours?

 

[flew62999]

Thanks for the help...
there was no specific as to the time...

I think I can solve it now.
Thanks again