As the U.S. participants start their journey today at airports across the country, images of long lines, tickets, large suitcases, and airplanes may come to mind. II weighed and repacked my bags several times this morning to make sure they were under the weight limit. Ever wonder why the airlines are so adamant about weighing your bag when you check in? Afterall, what difference does an extra bag make?
Turns out, plenty. If you take a look at the figure (or see http://www.grc.nasa.gov/WWW/K-12/airplane/Images/forces.jpg ), you'll see the four forces acting on an airplane: thrust, drag, lift, and weight. In order to get into the air, an airplane must overcome the forces of drag and weight. Weight also affects how well the pilot can control the plane. A pilot must constantly account for the weight distribution of the plane to keep it in the air and flying in the direction s/he wants it to.
To learn more about how planes fly, see http://www.grc.nasa.gov/WWW/K-12/airplane/Images/forces.jpg