Valley Jr-Sr High School Home

Wehen Mr. Edgerton launches potatoes in his science class they record each launch.  The videos are used to show that the velocity of the potatoes can be calculated using the distance each potato travels from one frame to the next, then dividing by the time each frame takes.  The iPhone videos at 60 frames per second, so each frame takes .01666 seconds to elapse.  All the videos show the potato traveling at 36.01 m/s or 80 mph.  Next we use two meter sticks attached to a speed square to measure opposite and adjacent to calculate the launch angle of the potato.  Combining the launch angle and velocity we can calculate how far the potato would go in a vacuum.  The final calculation multiplies the vacuum distance times a drag coefficient to accurately estimate where the potato will land.  Wind makes a big difference in how far the potato goes.  An 8 mile per hour wind will change its flight distance by 30 meters. We were attempting to make the potato travel 100 m, measured by the start and finish on the track, but with a head wind the potato would come up 20 meters short and with a tail wind it would overshoot about 10 meters.