I just got done with my Physice test and had a question on one of the problems I

Question

I just got done with my Physice test and had a question on one of the problems I couldnt figure out.....So here it is....I wont know if its right or wrong for a few days but would appreciate any input cause it drove me crazy.....the gave M=.5 K=100 and wanted to know the velocity of the mass at .03m   Heres my thinking...... I know that there are three forces acting in the y direction..... Ugrav, K, and Uel.....K=.5mv^2   Ugrav=mgy Uel=1/2ky^2 ....... I set them equal to each other   K1+Ugrav1+Uel1=K2+Ugrav2+Uel2.......but when I did this I noticed I plugged in a 0 for y1 where it started and a -.03 for y2........but when you plug in a zero then that is saying there is no potential gravity at the start, but that cant be right because its about to fall?   so i plugged in a .3 for y1 and a 0 for y2, but that didnt make sense either because it is still falling and has Ugrav2 potential...... So I decided to just pick a random y and plugged in y1=10 and y2=9.97...... but thats wrong because when I got home i plugged in a different y of 20 and got a different number......   I know there are three forces acting on the mass, please let me know what I did wrong, how to fix it, and also how to find the max velocity after it fell.....THanks

Explanation / Answer

can you give me details on the question I think its juts energy and momentum conservation,

see what are the initial energy if the mass is in air then take mgh, spring compressed then .5kx^2

and see to which form these will go and conserve accordingly

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