Could you walk across a swimming pool filled w/ ping pong balls?

[AlaskanMatt]

Hello,

I feel a little out of place here, as I have no physics background whatsoever, but I was hoping you folks here might be able to help settle a debate. My brother and I like to have "what if" discussions, and one we had quite awhile ago was whether a person could walk across a swimming pool filled with ping pong balls (EDIT: No water in the pool, only ping pong balls).

I said that it would not work, because the balls, being so light and having a smooth sphere shape, would cause a standard person to sink into the balls, and one would have to "wade through" them to get out of the pool.

My brother, however, insists that since the balls would be supported by the sides and bottom of the pool, they would support a person who could easily walk across.

If this is too unscientific of a question feel free to ignore or delete it, but this debate has been going on for quite awhile and I was hoping that someone more experienced in weight/friction/physics issues could explain what would happen better than myself. Thanks for your time,
Matt.

 

[Danger]

You are correct, and your brother not so much. Challenge him to walk over ping-pong balls on dry land and see how far he gets. Water just bitches it up a couple of notches.

 

[AlaskanMatt]

You are correct, and your brother not so much. Challenge him to walk over ping-pong balls on dry land and see how far he gets. Water just bitches it up a couple of notches.

I should have clarified: The pool is full of ping pong balls only, no water involved. But I don't believe either way would work...

Thanks for the response.

 

[Borg]

Yes, you would sink. When you walk, your weight is spread over the area of your feet. Assuming that your foot covers 10 balls and you weigh 150 pounds, each ball is roughly exerting 15 pounds of force in some direction when you take your first step. Since the other balls can't go down, this would result in them rising up around your foot and you would sink.

In order to walk on ping pong balls, you would have to spread your weight over a larger area by using snowshoes or something like that.

 

[Stonebridge]

We could always try looking at Archimedes Principle!
The standard mass of a ping pong ball is 2.7g and its diameter is 40mm
This gives it an effective density of about 0.08 g/cm³
The density of water is 1 g/cm³

Conclude from that what you will.

 

[cristo]

Ball pools wouldn't be much fun if you could walk on the surface!

 

[Hurkyl]

We could always try looking at Archimedes Principle!
The standard mass of a ping pong ball is 2.7g and its diameter is 40mm
This gives it an effective density of about 0.08 g/cm³
The density of water is 1 g/cm³

Conclude from that what you will.

I would think the question is about viscosity, not buoyancy.

 

[Danger]

Well, Matt edited his OP to mention that there was no water involved, but I still think that it can't be done. It would be extremely easy to "float" upon the balls in a horizontal position, but I can't see any way in which one could remain vertical.

 

[russ_watters]

Ball pools wouldn't be much fun if you could walk on the surface!

Yeah, jeez - have you guys never been to McDonalds?!

[PLAIN]http://www.sharkysweymouth.co.uk/images/ball_pit.jpg

http://www.google.com/search?source...rlz=1T4ADBF_enUS311US311&q=mcdonalds+ball+pit

 

[Danger]

Yeah, jeez - have you guys never been to McDonalds?!

Uhhh, no... and why have you?

 

[Stonebridge]

I would think the question is about viscosity, not buoyancy.

Me too. I was being mischievous.
Can you think of a simple order of magnitude calculation involving viscosity of ping pong balls?

 

[AlaskanMatt]

Yes, you would sink. When you walk, your weight is spread over the area of your feet. Assuming that your foot covers 10 balls and you weigh 150 pounds, each ball is roughly exerting 15 pounds of force in some direction when you take your first step. Since the other balls can't go down, this would result in them rising up around your foot and you would sink.

In order to walk on ping pong balls, you would have to spread your weight over a larger area by using snowshoes or something like that.

Exactly! At one point I mentioned to him that unless one was wearing something that made their feet very wide, it would be impossible.

I appreciate the responses everyone. Thanks for your help.

 

[Danger]

Any time, pal. Hang around for a while and get into some other neat ****. You strike be as being someone who will be a great PF member.