posted by Teri .
A pole-vaulter runs toward the launch point with horizontal momentum. Where does the vertical momentum come from as the athlete vaults over the crossbar?
Pole vaulters have three things going that help them clear a very high bar.
(1) The angular momentum about the place there the pole is stuck into the ground is preserved, which helps to push the vaulter upward. In order for this to happen, the pole pushes the vaulter upward.
(2) Flexible poles, which have been allowed since about 1960, store kinetic energy of the running vaulter as potential energy, which is released when the pole is vertical and straightens out again.
(3) When the pole is vertical, a skilled vaulter will push his or her center of mass upward, becoming upside down to gain an extra 3 or 4 feet of height, bending the waist as it passes over the bar.