Answer:
Step-by-step explanation:
The height of the rock as it reaches the ground is zero i.e f(t) = 0
Substitute into the function to get t first as shown;
f(t) = -2t^2 + 15.7t
0 = -2t^2 + 15.7t
2t^2 = 15.7t
2t = 15.7
t = 15.7/2
t = 7.85secs
Get the total distance travelled by substituting t = 7.85 into the modeled equation;
Recall that:
f(t) = -2t^2 + 15.7t
f(7.85) = -2(7.85)^2 + 15.7(7.85)
f(7.85) = -123.245+123.245
Hence the total distance travelled by the rock when it reaches the ground is 0m
