À stone is thrown
downward with intial
speed 8m)s from a height
25m. find
(a) the time taken to
reach the ground
(b) the speed with which it strikes

Respuesta :

a = -9.8

v = -9.8t -8

s = -4.9 t2 -8t +25

So… -5t^2 -8t + 25 =0, we’ll rearrange to 5t^2 + 8t - 25. We get two roots, one is positive and is 1.59 seconds

V = -9.8(1.59) - 8 = -23.6

So… it takes 1.59 seconds to hit the ground at -23.6 m/s.