Answer:
0.66secs
Explanation:
Given the following
Initial speed u = 24.2m/s
Height H = 18m
Required
Time t
Using the equation of motion:
H = ut+1/2gt²
18 = 24.2t+1/2(9.8)t²
18 = 24.2t+0.5(9.8)t²
18 = 24.2t+4.9t²
Rearrange
4.9t²+24.2t -18 = 0
Using the general formula
t = -24.2±√24.2²-4(4.9)(-18)/2(4.9)
t = -24.2±√585.64+352.8/9.8
t = -24.2±√938.44/9.8
t=-24.2+30.63/9.8
t= 6.43/9.8
t = 0.66secs
The ball will be at the same height after 0.66secs
