Answer:
option D
0 < t < 3
Explanation:
Given in the question the equation
d = 144 - 16t²
where d is the distance
t is the time
Since, it is a descent, d should be decreasing until it reaches zero
by plugging d = 0 in the equation
0 = 144 - 16t²
-144 = -16t²
144/16 = t²
t² = 9
take square root on both sides
√t² = √9
t = ±3
since time can't be negative so we will reject -3
t = 3
This means that at 3 seconds the roller coaster was at ground but before that it was in the air
so when t < 3 Greg's car was moving in the air.