An object is launched from the ground straight up with a initial velocity of 120 ft/s. how long will the rock be in the air?

t = 7.5 seconds

Step-by-step explanation:

Givens

vi = 120 f/s

a = -32 f/s

d = 0               It goes up, stops and comes back down landing where it starts.

Formula

d = vi*t + 1/2 a t^2

Solution

0 = 120*t - 1/2*32*t^2     transfer 120t to the left

-120*t = - 1/2 32 t^2        Multiply 32 and 1/2 together  

- 120t = - 16 t^2                Divide both sides by t

-120 =    -16 t                    Divide by -16

-120/-16 = (-16/-16) * t      

t = 7.5 seconds

8 2/3 is the answer

step-by-step explanation: just use a calculator