Answer:
The answer is C.
Step-by-step explanation:
Given formula h(t)=−16t2+v0t+h0 , where v0 is the initial velocity and h0 is the initial height.
In this case, the initial postion is a platform 30ft above ground so h0=+30
The initial velocity is 38 ft/s straight up into the air so v0=+38
h(t)=-16t2+38t+30
When the object hits the ground, h=0.
h=-16t2+38t+30=0
Simplifying 8t2-19t-15=0
(8t+5)(t-3)=0
t=-5/8 or 3
As time cannot be -ve, t=3s. The answer is C.
