From 18 m height above the ground a ball is dropped from rest. The height above the ground at which the magnitude of velocity equal to the magnitude…

From $\displaystyle 18$ m height above the ground a ball is dropped from rest . The height above the ground at which the magnitude of velocity equal to the magnitude of acceleration (in the same set of units) due to gravity is $\displaystyle \_\_\_\_$ m. (Take $\displaystyle g=10 \mathrm{~m} / \mathrm{s}^2$ and neglect the air resistance)