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surfrider2000
Joined: 12 Nov 2015 Posts: 1 Location: Pennsylvania

Posted: Sun Nov 15, 2015 3:18 pm Post subject: projectile motion using an altimeter 


I am comparing experimental and theoretical data of a projectile of a foam soccer ball (Flight 3361: mass=0.252 kg, diameter is 0.19 m, Cd=0.5) thrown by hand. The velocity of the ball is vox=13.597 m/s, voy=13.317 m/s. It was thrown at an angle of 44.7 deg from the horizontal. I measured altitude as a function of time every 0.05 seconds using an altimeter (good to +/ 0.3m...but in actual flight it can be +/0.6 or even +/ 1 m). Theoretical predictions were calculated: one that accounts for drag (using Euler's forward differentiation) and another that doesn't account for drag (kinematic equations). I compare theoretical data to the experimental data: 5.5m, 8.25m, and 10.5m for experimental, theory w/ drag, and theory w/o drag, respectively. I thought the theoretical prediction w/ drag of the altitude would be close to the experimental. An error of 49% seems high. Even if there was a error in the altimeter of +/ 1m, that still computes to 28% error between experimental and theory w/drag. Any thoughts? Do these values seem reasonable? 

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