Ok, here's the deal. I have a projectile motion project that goes a little beyond the normal "ideal projectile" problems.(adsbygoogle = window.adsbygoogle || []).push({});

The project consisted of shooting a projectile from a device that, within a few percent, launched a projectile at the same initial velocity every time it is fired. The launcher has an adjustable launch angle and shoots a ping-pong ball sized 5g projectile with a rough surface (yellow foam ball). My team shot the ball ten times at 15,30,45, and 60 degrees and then measure the distance traveled. We were told this data will be used later this week to find the drag coefficient of the ball but for today I simply need to develop a general equation of motion given:

[tex]v_0=100m/s,\ \theta=30^\circ,\ m_{proj}=20kg[/tex] and various values of K.

Also, the force of drag is described as [tex]F_D=-Kv^2[/tex]

where K is the drag coefficient and v is velocity.

I need to develop the equations of motion in terms of x and y for this "test" projectile which I will use later on to find the drag coefficient of our yellow ball and predict the range of the ball given an angle of launch.

I know I need 2 second order ODE's which I can convert to four first order ODE's, but I don't know where to start or how to start.

I have my FBD--a round ball with weight parallel to the y axis and drag opposite to the direction of velocity.

Any help would be greatly appreciated here. Thanks in advance.

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# Homework Help: A little bit beyond projectile motion.

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