I was there once. Essentially the question can be boiled down to one of 1-D kinematics. The acceleration is (wtf is this nigger-tier rounding of g?) 10m/s^2 and thus the equation of motion is y(t)=-1/2g*t^2+10m/s*t+25m defining up as positive. (youll learn how to get this in later classes, its essentially integrating with initial values of velocity and distance). In addition to this fomula, we have the velocity equation thats integrated to find the earlier one: v(t)=-g*t+10m/s. Solving the first for the time in the first eq when setting y(t)=0 you will find some value, say b, for when the y=0 (or in other words, it hits the ground). Plugging that back into the second equation will give you the velocity. Even before doing anything we know it must be a negative value.
Beyond this trivial garbage however, if you say you are a physics major- as I am too :), I recommend you really start learning more than you are taught in first year. The first year will mainly be calc 1-3 and lin alg (as well as retarded labs, two first level classical mechanics and electromagnetic, and even gay fucking chemistry). This much is simply not enough if you want to do really well. I suggest you use the resources found on this board- a haven in my view; go through the suggested materials on the front page sticky, start reading Feynman's lectures on physics, and LEARN PROOFS EARLY ON: I cant stress it enough, its a vital change in view and they are really fun. Once you learn the general gist of them, you will never take something you learn for granted- you will hunt for the proof, and most are really quite elegant and neat.
Finally, good luck with your studies anon. Theres much much more to physics than this elementary crap (trust me, we both know this kinematics garbage is boring but you have to get through it any way). I hope to see a bright physicist come of you in the future anon- godspeed.