Uses for parabolas

Well. I think that there are many uses for parabolas. Not just as trick questions on a test, but more legitimate, real life experiences. For instance, did you know that every time a dancer jumps, a parabola is made? They start on the floor, take off, sail through the air and come back down . If you could find the apogee of the jump and any point on the line if the jump, you would be able to determine the shape of the parabola and weather it was a vertical shrink or stretch. The higher the jump, the shorter the length of the parabola would be. If the center of the stage is (0,0) and a vertical and horizontal lines are "drawn" to form the Cartesian plane, the dancer(f(x)) leaps  two feet to the left of center, but still on that horizontal line, by accident, the equation of the dancer's jump would be dependent on the height, but the function form of the jump is f(x)= (x-2)2. 

                                      

Parabolas are in all sports. Everyone knows that the person jumping, diving or falling is making an arc, but only smart math geeks like us recognize that it isn't just arcs that are made, but  negative parabolas (concave down).