Integral [1;2] [1/√(2gh) * dh] =
1/√(2g) *integral [1;2] [1/√h * dh] =
1/√(2g) *integral [1;2] [1/(h^(1/2)) * dh] =
1/√(2g) *integral [1;2] [(h^(-1/2)) * dh] =
1/√(2g)* ( (h^(-1/2+1))/(-1/2 + 1) )| 1; 2 =
1/√(2g)* ( (h^(1/2))/(1/2) )| 1; 2 =
1/√(2g)* ( 2√h )| 1; 2 =
1/√(2g)* ( 2√2 - 2√1 ) =
1/√(2g)* ( 2√2 - 2 ) =
2/√g + 2/√(2g)