Answer:
It takes 3 seconds over the interval [0,3]
Step-by-step explanation:
To find when the roller coaster reaches the ground, find when d=0. 

To solve divide each term by 16 and factor:

Solve for t by setting each factor to 0.
t-3=0 so t=3
t+3=0 so t=-3
This means the car is in the air from 0 to 3 second.
 
        
             
        
        
        
Answer:
30 minutes.
Step-by-step explanation:
55 - 25 = 30 
Hope this helped, have a great day/night!