a girl throws a stone vertically upward with an initial speed of 8 m/s. How high will the stone rise? How long will it take to return to the ground after it is thrown?

Answer 1

that isnt much to go on, but try this:
h(t)=-1/2(g)(t^2)+Vt+h
(g=32ft/sec^2 or 9.8m/sec^2)
V=initial velocity
t=time
h=initial height
im assuming that this question is implying that the girl is standing on the ground, so for "h" no input would be needed.
that function up there is quadratic btw, so you could estimate the roots to find your answer. And possibly use a quadratic calculator, id give you a link if it would let me, but you could just google it...probably not too terribly helpful lol but I was kinda looking for a second opinion myself so...sorry :/