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 simply get the answer, but obviously that's not going to help me to solve slightly more advanced problems such as this!
Could someone please give me advice on how to approach this problem (and/or physics problems in general). Anything that can help me conceptualize these better. I just want to be able to solve these without staring at it for 5hrs...Thanks in advanced.