Why? The Science of Athletics

SOME MORE MATHEMATICS FOR ATHLETES 287 will assume that the thrower is physically equipped for the feat he wishes to perform. The only way strength need be considered is in relation to the fact that the stronger a man is and the more his strength is applied to an incorrect balance, the greater will be the resulting error. If this truism is borne in mind, its force will become more apparent as the question of balance is dealt with. We will deal with this point in some detail, since it is the most important one, and the one which governs the perfect throw. By balance one means, of course, centre of gravity. A body will be in stable equilibrium when it is so suspended that a slight swing to either side will cause it to oscillate c . I t A t B FIG. 104 gently until it comes to rest again with its centre of gravity vertically under the point of suspension. Fig. 104 represents a javelin, drawn somewhat out of proportion for the purposes of illustration. Let c be the centre of gravity of the whole javelin ; if it be suspended or balanced at this point it will remain in equilibrium. This now divides it into two parts (not of equal lengths), each of which, again, has a centre of gravity at a and b respectively ; and it is the~e two centres of gravity which keep the whole weapon in equilibrium when held in the thrower's hand. Now, the force applied in. throwing the javelin must pass through its centre of gravity, i.e. at c, which is the centre of the weight of the whole body. (See application of power through grip-binding, Figs. 106, 107 and 108, Plate 23.) · _ But supposing the javelin be thrown with the · hand grasping it at _b, then, as just stated, the whole weight to be moved lies in c, and therefore any force applied