High Dive Problem

[vhawk01]

This is at least nominally a physics problem, but I suck at physics. What I'm wondering is, is there some reasonable assumptions or estimations I can make in order to try and determine the minimum depth of water, x, necessary for a safe dive from some height, y? I know there is some technique involved, so this will be a crude approximation. Anything +/- ten feet should be close enough.

Yes, this is related to a drunken bar bet and no, you do not need to worry about paralyzing vhawk with too conservative an answer.

[btmagnetw]

a good benchmark is 1 ft of water per 10 ft of dive. good luck.

[vhawk01]

[ QUOTE ]
a good benchmark is 1 ft of water per 10 ft of dive. good luck.

[/ QUOTE ]

[img]/images/graemlins/grin.gif[/img] Like I said, yer not gonna kill me, I'm not actually diving into anything.

[samsonite2100]

[ QUOTE ]
a good benchmark is 1 ft of water per 10 ft of dive. good luck.

[/ QUOTE ]

Unless you're joking, this is obviously incorrect.

[Neuge]

[ QUOTE ]
[ QUOTE ]
a good benchmark is 1 ft of water per 10 ft of dive. good luck.

[/ QUOTE ]

Unless you're joking, this is obviously incorrect.

[/ QUOTE ]
http://www.youtube.com/watch?v=jSXzBSPQ50k (rickroll?)

[samsonite2100]

I didn't realize the question was "what's the minimum depth of water necessary for a belly flop into a kiddie pool perched on top of a bunch of foam." In that case, the correct answer is "no water."

[Siegmund]

Assuming we are talking about "serious" diving, where you actually try to enter the water cleanly and get to a reasonable depth, I would take as a starting point:

Your speed of entry into the water is going to be roughly proportional to the square root of the height from which you dive;
Diving from the side of the pool is marginally safe in about 5 feet of water (dangerous enough so that you'll be told not to do it, but safe enough you can if you arent trying to dive super-deep.) Your center of mass is between 3 and 4 feet above the water when standing beside the pool.

Sooo... I will propose 2.5*sqrt(height of platform + 4) as a first attempt.

In the real world, I've seen 12-foot high dives above 12 feet of water (my formula says 10 feet is safe) and 30-foot high dives above 15 feet of water (my formula says 14.5 is safe).

My understanding is that divers actually cease holding their "deep-diving" configuration as soon as their feet are in the water, and either spread out into a higher-resistance body form, or actively swim for the surface -- my impression is that dives from considerably higher than 30 feet are done into 15 feet of water.

[vhawk01]

[ QUOTE ]
Assuming we are talking about "serious" diving, where you actually try to enter the water cleanly and get to a reasonable depth, I would take as a starting point:

Your speed of entry into the water is going to be roughly proportional to the square root of the height from which you dive;
Diving from the side of the pool is marginally safe in about 5 feet of water (dangerous enough so that you'll be told not to do it, but safe enough you can if you arent trying to dive super-deep.) Your center of mass is between 3 and 4 feet above the water when standing beside the pool.

Sooo... I will propose 2.5*sqrt(height of platform + 4) as a first attempt.

In the real world, I've seen 12-foot high dives above 12 feet of water (my formula says 10 feet is safe) and 30-foot high dives above 15 feet of water (my formula says 14.5 is safe).

My understanding is that divers actually cease holding their "deep-diving" configuration as soon as their feet are in the water, and either spread out into a higher-resistance body form, or actively swim for the surface -- my impression is that dives from considerably higher than 30 feet are done into 15 feet of water.

[/ QUOTE ]

Excellent, thank you. This is along the lines of what I was looking for. You may have just won me a free round.

[vhawk01]

[ QUOTE ]
[ QUOTE ]
a good benchmark is 1 ft of water per 10 ft of dive. good luck.

[/ QUOTE ]

Unless you're joking, this is obviously incorrect.

[/ QUOTE ]

Yeah, I think he was joking/trying to kill me. Its cool either way.