Thread: projectiles equation confusion

there are two equations v=u+at and s=ut+(1/2)at²
from the first question ,if we set the time to v=0 to find time(t)(which is half of the flying time),
we get
0=u-(g/2)t
(g/2)t=u
t=2u/g ----- (1) to find the total,we have to multiply by 2. so t=4u/g
when the displacement is 0,we can find the total flying time using:
s=ut+(1/2)at²
0=ut-(g/2)t²
t{u-(g/2)t}=0
(g/2)t=u or t=0
t=2u/g ,not 4u/g

aren't both equations suppose to give the same answer?

NEVER MIND.Problem is solved! .how to mark this as solved?

In the upper right of your first post click on thread tools. Mark as solved should be one of the choices.

ah ok,thanks