Gravity Needed to Dunk a Basketball

The geek in me is coming out in this post.  The other day the following thought popped into my head.

"I can't dunk a basketball.  I wonder what gravity on Earth is necessary for me to dunk a basketball?"

Yep, total geek right here.  :-)  A basketball rim is exactly ten feet high and I figure I need at least an additional 6 inches to dunk the ball.  Therefore, I need a reach of 126 inches.  Right now I can brush the bottom of the net, which hangs about 15 inches below the rim.  Thus I need another 21 inches in reach.

The average vertical jump is about 17 inches and I figures I'm about average.  I figured out the initial velocity I have to reach that height using standard equations of motion.  Using that velocity, I determined the acceleration of gravity, g, needed to reach an additional 21 inches.

I need the acceleration of gravity on Earth to be 4.39 m/s^2, or about 45% of the current value of 9.81 m/s^2.  Ug....that's depressing!