Help with my ??? Hello! I am new to this site and I didn't know that their was online help for physics. I don't want anyone to do my work first off, I WOULD LOVE HELP to understand it better. I am currently enrolled in Physics and I am having problems with understanding it fully. I can get half way and then I just go blank and I don't understand why..so i just would really appreciate if someone can give me a better understanding.....for instance i have two problems that are confusing me... 1. I am currently doing a problem on freely falling objects...my question is do i convert first before trying to solve it completely because my teacher said that if we convert first then we should not get stuck, but the fact is which one should i convert...such as if a ball is dropped out of a 120 cm window and it takes it 0.125 s to hit the bottom from the top and then it collides with a horizontal sidewalk and reappears at the bottom of the window 2.0 s after passing it..and my solution that i am looking for is how tall the building is. So far I started to convert the 120 cm maybe to m, because when it said how tall i know that it will come out to m because it is asking for the height of the building or either it can be in ft. So i got stuck afterwark because i don't know which formula i need to use after that such as, v=v0t-1/2 gt^2. i might be wrong, but i'm stuck so can someone please help me on that understanding.