Originally posted by: spidey07
Originally posted by: DrPizza
Originally posted by: LS21
it is *practically* water proof... because i cant see most people diving below 100ft... and if they did they would already have real serious equipment including "real serious" diving watches
Yep. I can't see 100ft plus swimming in current being anywhere near the pressure experienced at 330ft
Every 33 feet is equal to one atmosphere, so 330 feet is 10 additional atmospheres of pressure. i.e. an extra 147psi. At 100 feet, that's 3 extra atmospheres; roughly an additional 45 psi above surface atmospheric pressure at sea level. I can't see how swimming and current could possibly add 100psi to what the watch case experiences.
Physics and fluid dynamics is not your strong point I see? *tongue firmly implanted in cheek.*
Think about it for a while. Push your arm quickly through water and tell me that force isn't way above 1 atm.
Physics is my strong point - I teach physics. However, admittedly, I haven't studies fluid dynamics in 22 years, nor have I used fluid dynamics in 20 years. Nor do I teach any fluid dynamics, except to explain to my students how Bernoulli's principle isn't enough to make jets fly, no matter what the idiots may say because they remember their 4th grade teacher telling them that it's Bernoulli's lift that keeps them in the air.
However, I'm not sure if you're aware of this or not, but atmosphere's are not a unit of force. Atmosphere's are a unit of pressure. Pressure is force per unit of area. I see that fluid dynamics isn't your strong point either. My, arm has a lot of surface area, so even a small pressure is going to translate into a larger force.
I do realize that there's an increase in pressure on the leading side of an object moving through a fluid (with a viscosity; which is any normal fluid, including air, and which excludes liquid Helium becoming a "superfluid".) Without a difference in pressures front to back, there wouldn't be drag.) And, I recall that there's a difference between static pressure and dynamic pressure. But, I still wouldn't think that the dynamic pressure is that great of a difference.