Question

An object is launched from ground level with an initial velocity of 400 feet per second. To the nearest tenth of a second, how long does it take the object to reach a height of 650 feet?

Answer 1

use one of the equations of constant acceleration
s = 650, u = 400, a = -32 (acceleration due to gravity), and we need time t

we use s = ut + 0.5 at^2:
650 = 400t - 16t^2

solve this for t

can you do that?

Answer 2

the value of t you want is the lower one