The velocity of freely falling body changes as $g^ph^q$ , where g is acceleration due to gravity and h is the height. The value of p and q are 

$\frac{1}{2} , \frac{1}{2}$

Dimension of velocity v = dimension of $g^ph^q$

$M^0LT^{-1}$=$[MLT^{-2}]^p[M^0LT^0]^q$ = $M^0L^{p+q}T^{-2p}$

Comparing exponent from both sides

p+q = 1

-2p = -1 ⇒p= $\frac{1}{2}$ 

⇒q= $\frac{1}{2}$