# Number of moon rocks

My team was wondering, is there a limit to the number of balls you can hold on your robot at one time? Our team has been thinking that there was a limit of seven, due to that being the number you can start with, yet we can’t find any mention to a limit otherwise. Can anyone clarify this?

Thanks on behalf on Team 1569

I believe the only limit to them, is 7 at the begining of the match, then you can get as many as you can hold.

Thank you very much!

Plus one empty cell.

your robot can start with those first initial 7 balls in the begining. after that your robot can hold as many balls as you want, in fact your robot could hoarde all 120 balls if you wanted (but that would be quite difficult)

your robot can also carry one empty cell at a time, this is the only limitation that is listed in the rule book on ball handling.

-Avinesh-
-Team 1778-

Just sort of a nitpicky math note =) - surprisingly, it is in theory possible to hold all 120 balls, as was previously suggested.

r = 4.5 in^3
4/3 * pi * r^3 = 381.7 in^3 per ball

28 * 38 * 60 = 63840 in^3 total volume in sizing box

381.7 * 120 = 45804 in^3 total volume taken up by balls.

Of course, in practice, each ball will occupy at least a 9x9x9 box (think about how you would stack them if you were to try to pack them in as close as possible), which translates to:

729 in^3 per ball

729 * 120 = 87480 in^3 taken up by balls

And yes, you could hold a few outside of your sizing box, but not, say, 20.

AND you of course need space for battery, chassis, mechanisms, etc.

Short answer - everyone has been 100% correct in the rules - after the match starts, you could have as many moon rocks as you can hold. However, (in my opinion) any robot that is designed to hold more than 30 balls is probably sacrificing too large an amount of space to be practical, and for no discernable gain.

-Paul

well, the design me and my group have created can hold anywhere from 26-46 balls. we didnt have to sarafice anything becuae that is our main portion of our bot…

You might want to think about this some more, consider if the balls are allowed to “nest”, rather than sitting directly on top of, and next to, each other as a stack of boxes would. I think you could fit some more balls in there!

Hmm. I think I stick by my original claim. I don’t have enough orbit balls to model this, and my spacial reasoning isn’t good enough to come up with a mathematical proof, but I don’t think the nesting gets you anywhere - you’re still going to have just as much empty space.

Of course, moot discussion for the purposes of the game, but still worthwhile.

-Paul