My mom used a pressure cooker for roasts when I was younger. Not sure exactly what make and model it was, all I remember is that it had a weight that sat on a hollow post on the lid and released pressure. I can still hear it spinning around... Shhh-shhh-shhh-shhh-... I remember her using it mainly for pot roasts, which were always flavorful and tender.
To continue on with Goodweed's safety lecture... If you apply that 785 pounds of force to a (lets be generous) 2 pound lid, for a fraction of a second (say, 5 hundredths of a second, because the force is applied ony until the pressure is released, and that will be a very short time) you wind up using this formula: F= M X A Which is Force = Mass x Acceleration. Now we solve for Acceleration: F/M = A and therefore 785/2 = A. Well A is the change of velocity over change in time so we get:
785/2 = (V1 - V0) / (t1 - t0)
Well, we know three of these. Initial velocity (V0) is zero. Time start (t0) is zero. And time elapsed (t1) is .05 seconds.
Which gives us 785/2 = (V1) / .05 Or 785/2 x .05 = V1.
Or a velocity of 19.625 feet per second, given the data we started with (which is arbitrary at best).
To put it in perspective, that's right about 13.4 miles per hour.
The acceleration it undergoes 19.625 ft/sec x 1/.05 sec = 19.625/.05 ft/sec^2 = 392.5 ft/sec^2.
Roughly 12 g (Where g is the gravitational constant of the Earth.)
Thats right about 3 times the acceleration the Space Shuttle experiences during launch. Of course, the Shuttle experiences that for a lot longer otherwise putting things (like pressure cooker lids) into orbit would be easy. So if you want to experience having a 2 pound lid go from zero to 13.5 miles per hour in literally a blink of an eye, in the middle of a large cloud of steam, go right ahead... Just let me know ahead of time so I can be close enough to enjoy the show, while far enough away to avoid steam and the returning lid.
Who says you'll never use algebra in cooking? (I just hope I got it all right, it's been forever since I tried using this stuff).
Too bad there're no and [super][/super] tags...
