Arocket is launched from atop a 99-foot cliff with an initial velocity of 122 ft/s.
a. substitute the values into the vertical motion formula h = -16t^2 + vt + c. let h = 0.
b. use the quadratic formula find out how long the rocket will take to hit the ground after it is launched. round to the nearest tenth of a second.

8.4 seconds

Step-by-step explanation:

For (a) we have h=0 and t=0    

when we substitute the values we get

Which will give the value c=0

Now, to find how long the rocket will take to hit the ground after it is launched

we get  

We will solve the above quadratic equation for t we get:

We have formula to solve the quadratic equation:

Here, a=16, b=-122 and c=-99

On substituting the values in the formula we get:

Now, we will substitute D in the formula to get final value of t

We will neglect the negative time

Hence, 8.36 seconds or approximately 8.4 seconds

(a) the volume of the cone is 20/3 in3

hence, option a is correct.