Answer:
At the maximum height of the vault
Explanation:
The formula for gravitational energy (GPE) is
GPE = mgh, where
m = the pole vaulter's mass
g = the acceleration due to gravity
h = the height above the ground
Since m and g are constant,
GPE ∝ h
The point of highest GPE is at the maximum height of the vault, just before he starts falling towards the ground.
