Rocket Launching

from physics teacher Mark Schober

Juniors in the regular physics course built, launched, and analyzed water rockets in terms of impulse and momentum. Their engineering goal was to send an egg as high as possible while ensuring its safe landing. Prior to the launches, students performed static thrust tests by launching bottles filled with different amounts of water into a force plate, allowing determination of the amount of water that produces the largest impulse. A "suck-down" wind tunnel is used to determine the velocity dependence of the air resistance on the rockets. Each launch was recorded with a new high-speed camera (thanks to the Parents Council) capable of 300 frame-per second video. Students perform video analysis of the thrust phase of the launch to determine the burnout velocity, which in many cases exceeds 100 miles per hour, while triangulation was used to determine that top rockets reached an altitude of 250 feet. Student analysis requires integrating their measurements into descriptions of how the impulse-momentum theorem applies to the launch of the rocket and to the protection of the egg throughout launching and landing. Some eggs even survived multiple launches!

Photos courtesy of Andrew Newman (fine arts, school photographer):