Take the tour ×  So I was given the following homework problem:
You land on an unknown planet somewhere in the universe that
clearly has weaker gravity than Earth. To measure g on this
planet you do the following experiment: A ball is thrown upward
from the ground. It passes a windowsill 15.0 m above ground and
is seen to pass by the same windowsill 2.00 s after it went by
on its way up. It reaches the ground again 5.00 s after it was
thrown. Calculate the magnitude of g (the acceleration due to
gravity) at the surface of this planet.  I found a solution on
answers.yahoo.com, but I still don't really understand it as
well as I would like.  I drew a picture and know that after 15m
it takes 2secs to fall back to 15m and then an additional 5secs
until it hits the ground. I can't assume that the velocity is
uniform for entire trip can I? (e.g. 6secs travel time going
both up and down/quadratic curve, for total 12secs) I have the 4
equations of kinematics and usually I just look where I can plug
in values and sim