a cricket player crosses a ball vertically upward with an initial velocity of 12m/s. a) how long does it take to reach maximum height, b)how long does the ball take to reach 7m above release point take g to be 10m/s
v = Vi - g t
0 = 12 - 10 t
t = 12/10 = 1.20 seconds to top
h = 0 + Vi t + (1/2) a t^2
7 = 12 t - 5 t^2
5 t^2 - 12 t + 7 = 0
(5 t - 7)(t-1) = 0
t = 1 or t = 7/5
so 1 second on the way up, later on the way down.