Athletics of To-Day 1929

Athletics of To-day Before going any further with the description of the vaulting action we will pause for one moment to consider the question of speed and power, as promised above. In this matter the diagram in Fig. 25, page 241, should help us a lot, while the calculations will no doubt interest those of my readers who have looked into the scientific side of athletics. To determine the effect of approach speed upon..the height the athlete is able to, or should, clear, it is necessary to find the height to which a body will rise against gravity, when its hori– zontal velocity is converted into vertical velocity. Let us assume that a pole vaulter approaches his take-off at a rate of 25 ft. per second, i.e., roo yards in r2 secs. The symbols in our calculation shall be v = velocity, h = height obtained, g = acceleration due to gravity, and t = the time taken for a body with velocity v to reach a given height. Then (i) v = gt; or t = H secs. (ii) Now h = tgts . . h = t X 32 X ? ~ : = 2 11 • feet. = 9.76 ft. or 9 ft. 9 ins. But this height obtained applies to the centre of gravity of the body in question. Assuming the centre of gravity of a man when running is at the mid-point of a line drawn between the upp r ends of his f mur it would be approximately 3 ft. from the ground and the line of his take-off, and should be raised by merit of his speed of 25 ft. per second to a h ight of 9 ft. 9 ins. + 3 ft. = r2 ft. 9 ins. If, how ver, the vaulter is capabl of running roo yards in rr s cs., i.e., his approach run is made at a speed of 27.3 ft. per second, then the h ight his found to be II.7 ft., so that he should be able to raise his centre of gravity to, and cl ar a crossbar at, 14 ft. 7 ins. These figures r late purely and simply to the m rit of the spe d of run-up, and such factors as friction of the pole point and air resistance have not be n allowed for, and the latt r is a very large factor indeed, which must have an adverse effect upon the height obtained. On the other hand, no favourable