
The water jet’s horizontal distance \( D \) from the hole to the point where it strikes the ground depends on the velocity of the jet at height \( h_1 \) and the gravitational pull. The velocity at the hole is given by:
\[ v = \sqrt{2gh_1} \]
This is the velocity of the jet when it leaves the hole at height \( h_1 \), as the velocity is due to the gravitational potential energy being converted into kinetic energy.
The maximum horizontal distance \( D \) occurs when the jet’s flight time and horizontal speed are maximized.
The maximum horizontal distance \( D \) is greatest when the height of the hole is maximized, i.e., \( h_1 = h \). Therefore, the maximum value of \( D \) is:
\[ D = h \]
Thus, the maximum value of \( D \) is indeed \( h \).
