Success in Athletics and how to obtain it

116 SUCCESS IN ATHLETICS giving a spring. His subsequent path will be along the arc a d. Now, at the moment when the pole strikes the ground at c, the fact of the man jumping converts the direction of the force, due to his run, to an up– ward one. Let us assume for the moment that his weight is about 1 SQT pounds. Diagram 17. Then referring to the diagram it will be seen that there are two forces at work simultaneously-one along the line a b, representing an energy of 937 foot– pounds, due to his weight and the velocity at which he was travelling, and another along the line a e, which is equal to 6oo foot-pounds; due to the energy of his spring upwards. Forming these two line~ into a parallelogram, a b d e, we get a resultant along the line ad, showing a kinetic energy of 1,120 foot-pounds and its direction, which is the force existent at the moment of starting, along the arc a d.