The formula gives the height of an object in free fall at time t and acceleration g.

[tex]h = \frac{1}{2}gt^{2} [/tex]

Solve for t.
[tex]t = (2gh)^{2} [/tex]
[tex]t = 2 \sqrt{gh} [/tex]
[tex]t = \frac{ \sqrt{gh} }{2} [/tex]
[tex]t = \frac{ \sqrt{2hg} }{g} [/tex]

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