Tuesday, May 14, 2013

First Screens Created With Tracker Program

I am trying to learn how to use the Tracker video analysis programs with video shot from a water rocket launch. Using a manual method of a tape measure and a stop watch would be impossible for an object as fast as a water rocket. The rocket is only in video viewing area for a 1/10 of a second which gives 3 frames of video when recorded at 30 frames per second.

Rocket at Rest

Frame 1

There is so much to learn with the Tracker program but I think I am finding through the very basics. I did not have a meter stick for a reference so used a yard stick which is buried 6 inches into the ground, giving a reference of 30 inches. The Tracker program should be calibrated to that for this video.

Frame 2

The data and graph seem reasonable showing the rocket slow to start trying to overcome inertia and really accelerating in the second frame, this is where all the water is expelled. By the third frame the rocket has slowed only slightly, it is now coasting on kinetic energy. Friction and the force of gravity will slow the rocket down until it reaches the apex and returns to earth.

Frame 3

I really want to learn this program because I think it could be a great learning tool and force me to revisit math that I have become rusty with.  No doubt there are some inaccuracies with this method but I think for learning theory it is useful.

My Calculations on Velocity of the Rocket

Maybe this can be done through program but I have not figured out how yet. This is what I got doing the math.  Average speed 55 mph, first segment 33 mph, second segment 96 mph, and final segment 70 mph.  I had read somewhere that a water rocket can be going over 100 mph a few feet after launch so I think my calculation sound reasonable.

My Blog post about finding Tracker Program
My Website Article on Water Rockets includes template for fin of water rocket

Bill Kuhl

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