Question

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?

Answer 1

The answer is actually C. 7.5 I just answered this question on a quiz. I'm sorry for the late response and I hope this helps!

Answer 2

t = 7.5 seconds

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