I’d appreciate you keeping your insulting personal characterizations to yourself.
Moderating
I was actually giving you the benefit of the doubt that your offense was due to obliviousness to how it might be taken rather than snark. Otherwise I would have presumed that your original post was intended to be deliberately insulting, and it would have merited a warning for being a jerk.
I’m instructing you to stop posting in this thread. If you have any further issues, take them to ATMB.
Colibri
General Questions Moderator
Back to the topic at hand…
Actually, the answer(s) to the OP’s question are not at all obvious. There are a lot of ways to interpret the questions, hence looking for “math geniuses” isn’t a bad way to start.
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You could measure the mass of the ball, which would be the mass of the plastic cover plus the mass of the volume of air inside. But then there’s a buoyancy force, which would affect the weight.
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There are other fluid dynamic factors, once the ball gets going, as mentioned by Machine Elf.
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Then there are factual answers, such as how big is this ball, how is it measured, etc. as figured out by other posters.
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Then…note that the darn thing will float if it goes into the water, thanks to water being considerably heavier than air.
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And if the ball were filled with helium it would float away, and yet, still have a substantial mass. This is weird but helps illustrate the difference between “mass” and “weight.” Making this ball a good teaching tool.
And then there’s the issue that weight doesn’t actually include the buoyant force: Weight is, by definition, the force exerted by gravity. What a scale reads will be affected by buoyant force, but then, it’ll also be affected by any other force that’s partially supporting an object (if I put my feet on a scale but my butt on a chair, I wouldn’t say that means my weight is 20 lbs).
The beach ball will be the weight of the plastic. The surface of a sphere is related to radius squared. (A=4pir^2 ) So a 9-foot diameter beachball will weigh 81 times as much as a 1 foot ball (roughly) assuming the same thickness of plastic. It’s 254 square feet (r=4.5’) of vynil, so 12 by 20 feet of plastic. If I pull a number out of my butt - say, about1/4lb - then the big ball will weight 20lb. Thicken the plastic and the weigh goes up.
I suspect the “flattening everything in its path” problem is probably more due to momentum (20lb is not trivial) and the fact that it will pick up the wind. Even a mere 20lb coming at you at 10mph with the force of a 9-foot diameter sail is not trivial wind can be pretty powerful, and many things are not meant to be hit from the side and stay up. .
Now I want one, too. Really 12’ diameter if possible. I would start to worry about it developing all sorts of leaks, though, and that a tougher material like nylon or polyester would be even heavier and much more expensive.
Under Item Weight it says “14.4 ounces.” We got the 8’ version of this once for a church picnic. It was printed to look like a globe, and the kids had a blast with it.
Nobody got knocked down or bowled over, and these descriptions of 30+ pounds of force as it rolled around do not at all ring true. Children as young as four years played happily with it and bounced it into the air. The only trouble we had was how unwieldy it was, and how easily the wind caught it. Fortunately we were in an area surrounded by hedges so it couldn’t blow off.
But yeah, no, it didn’t roll toward us with any more force or collide like anything more than a thin sheet of plastic. There was maybe a small “bounce” pressure that was a bit more than that. But nothing uncomfortable.
Sorry to disappoint.
Gee whiz all this calculatin’ stuff is making my brain hurt.
So I just wanna say there is another important question here: one which was raised, and answered in the OP’s link, (in the comments section):
That is all.
Carry on.
My wife was Girl Guide leader and sometimes we would weekend at a big permanent camp that had all kings of adventure stuff like abseiling, archery, canoeing etc. They also had one of these huge balls.
It certainly wasn’t 12 feet diameter, more like nine, but of course, it would not have been blown up hard enough to maintain a globe shape, so the diameter at the equator so to speak might well have been more. The camp only allowed it to be used in a small(ish) field with high hedges and not on windy days. There had to be at least two adults present and preferably more. The girls (aged nine to mid-teens) all found it great fun, albeit totally exhausting. The usually game was to organise two items who had to push it to the “goals” at either end.
The main danger seemed to be the risk of suffocation if a girl ended up on the ground with the ball on top of her. Most of the (minor) injuries were just what you would expect when a bunch of energetic young girls are e̶n̶c̶o̶u̶r̶a̶g̶e̶d̶ allowed to push and shove with few actual rules.
My wife was Girl Guide leader and sometimes we would weekend at a big permanent camp that had all kings of adventure stuff like abseiling, archery, canoeing etc. They also had one of these huge balls.
It certainly wasn’t 12 feet diameter, more like nine, but of course, it would not have been blown up hard enough to maintain a globe shape, so the diameter at the equator so to speak might well have been more. The camp only allowed it to be used in a small(ish) field with high hedges and not on windy days. There had to be at least two adults present and preferably more. The girls (aged nine to mid-teens) all found it great fun, albeit totally exhausting. The usually game was to organise two items who had to push it to the “goals” at either end.
The main danger seemed to be the risk of suffocation if a girl ended up on the ground with the ball on top of her. Most of the (minor) injuries were just what you would expect when a bunch of energetic young girls are e̶n̶c̶o̶u̶r̶a̶g̶e̶d̶ allowed to push and shove with few actual rules.
The hedges would be a very good idea. My thought was, how do you hold and contain a 9-foot diameter inflatable? 12 feet makes the question even more difficult. The least wind and it will go rolling away unless there’s a high fence or hedge to restrain it. If it’s like a beachball, there is no handle or grab point. You just have to be lucky the inflation nozzle is within reach, and even then it would take a while to deflate. Do not use with a noticeable wind…
(Yes, I saw some people on the news playing with a giant globe like this during one of the Earth Day celebrations quite a few years ago. )