A penny is dropped down a well. One hears the sound of it hitting the bottom 2.5 seconds later. If sounds travels at 330 m/s, how deep is the well. What I did: Time(penny)+Time(sound)=2.5 T(p)=2.5-T(s) T(s)=x T(p)=2.5-x d=vit+1/2at^2 330x=1/2(-9.8)(2.5-x)^2 I then solved using the quadratic forumula and got -62.2 or-0.102. I then chose the 0.102 seconds and multipled it by 330 and got 33.7 m. If this is right, my question is how can both times be negative, and how can you decifer which one is right besides using common sense?