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I'm doing a lab for engineering class, and I'm having a little trouble with a part of it. The lab was that we have a cannon on a table, with 3 launch settings (different lengths the spring is compressed). The table is 40" high. Also, we have a dixie cup 90" away from the table that we have to shoot the ball into. The problem was to find the angle to put the cannon at so that the ball lands in the dixie cup.

The problem I'm having is with finding the initial velocity of the ball out of the cannon. The spring constant is 235 N/m, and the amount the spring is compressed is 0.123825 m. The ball weighs 67 g. Now, we did the experiment in class, and the angle was around 61 degrees (we just found out with trial and error), and I think i can figure it out with calculations once I get the initial velocity, but how do I find that? Thanks a lot in advance for your help.

~Frank~

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# Initial velocity out of a cannon

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