## Calculating the launch speed from a launch angle, distance, and air density

Greetings to all.

First off, I apologize if I come off as an idiot here who has no idea what he's talking about (probably because I don't). My career is basically as a graphics designer, programmer, and musician- in that order (I design and build iOS applications for a living). I understand enough math to get certain things done in the computer (usually 3D/OpenGL related shader stuff), but physics has never really been a strong suit for me and I'm totally lost at the moment.

Anyways, a while ago I was contacted about building a sports-related application. As I'm sure most of you are aware, ideas are worth a dime a dozen unless you have a solid implementation behind it. So off I went into physics-land to try and figure some stuff out, and quite frankly- I don't even know where to begin.

The general gist of what I'm trying to achieve is this- I need to be able to figure out the launch speed from a launch angle, distance travelled, and an air density. Then I need to be able to run that again with the launch speed, launch angle, a different air density- and figure out exactly how far the object would travel (this is a travel related app that primarily deals with changes in elevation, temperature, humidity, and barometric pressure- then tells you how to compensate in the sport accordingly).

As I said, I'm totally and utterly lost here.

I'm not asking for someone to do my job here for me- but what I would be very appreciative of, is some pointers on where to begin with this stuff. I don't mind reading, I don't mind researching, and I have no quams figuring this stuff out for myself. There just seems to be so much of it, and I'm not sure what to selectively focus on to complete the task at hand as efficiently as possible.

Thank you in advance for any and all replies.

-CMPX
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 Good place to start would be for you to look for kinematics equations. (Google it you will find tonnes of reference). You are solving this in 2-D. So, you would just break kinematics equation in two component x and y. high school physics textbook may be good for that if you can get hold of it. de-acceleration depends on aero-dynamics of the object and perhaps other properties. So for that you might want to create post in 'mechanical engineering' section.