Why? The Science of Athletics

SOME MATHEMATICS IN ATHLETICS 267 jumper, for example, can calculate what should be his maximum elevation in jumping if he is to reach certain · given distances and can assess also the force and the energy he will be employing. If the reader will examine Fig. 93, what follows after will be more easily understood. · The point A represents the ordinary take-off board sunk flush with the ground. AB denotes the correct sprinting angle of 75- degrees which the jumper holds during his approach run and at which his body should be pitched when he is taking-off. Let it be noted that the line of the body's c B A TAKE OFJA BOARD~ ~- _____ REDUCED RANGE ---- ~ I ~------------FULL RANGE----------~ I FIG. 93 forward inclination AB and the ground line AD form the angle BAD, which is an angle of 75 degrees. The line AC indicates the true direction of take-off, and, with the ground line AD, forms the angle CAD of 45 degrees. This, in its turn, produces the true parabola of flight AHD, which is the path of the jumper's centre of gravity. If the jump is made at an angle greater or less than 45 degrees the · range will be reduced, as shown at E. H is the maximum vertical height attained when the jump is made at the true departure angle of 45 degrees. This height can be calculated for any jump. A proper body inclina– tion at the take-off brings the jumper's centre of gravity beyond the board and ensures that his high point will be reached at 2j3rds of the parabola of flight, and not half– way, which would cut down the clearance distance.