Step 1: Identify the vertical component of velocity.
At height \(5 \, \text{m}\), velocity is
\[
\vec{V}=5\hat{i}+5\hat{j}
\]
So, vertical velocity at this height is
\[
v_y=5\,\text{m s}^{-1}
\]
Step 2: Use vertical motion equation.
From height \(5 \, \text{m}\) to maximum height, final vertical velocity becomes zero.
So,
\[
v^2=u^2+2as
\]
Here,
\[
v=0,\quad u=5,\quad a=-10
\]
Therefore,
\[
0^2=5^2+2(-10)s
\]
\[
0=25-20s
\]
\[
20s=25
\]
\[
s=1.25\,\text{m}
\]
Step 3: Find maximum height from ground.
The ball is already at height
\[
5\,\text{m}
\]
Additional height gained is
\[
1.25\,\text{m}
\]
Thus, maximum height is
\[
H=5+1.25=6.25\,\text{m}
\]
Step 4: Final conclusion.
Therefore,
\[
\boxed{6.25\,\text{m}}
\]