Recent content by zzinfinity

Suppose I have a room of 100 people, 10 of which are women. What is the probability that a group of 5, selected at random, are all women. Is it (.1)^5 or is it (10/100)*(9/99)*(8/98)*(7/97)*(6/96). Or is it something else? Also any references to help me understand this question better...

Thanks! That was exactly what I was looking for!

How to "Offset" a polynomial Suppose I have a function for a curve, for example y=x2. I want to find a function to "offsets" it by 2 units. That is, I want a larger parabola that is exactly 2 units away from my original parabola. What I have in mind is the offset command in AutoCAD. Is...

Nevermind. You were exactly right. Sx=I/ymax. http://www.wikiengineer.com/Structural/BendingStress

Hi, I'm trying to calculate the maximum bending stress in a beam with a varying cross section. I found a great resource (link below) that gives examples on how to do this but am a little confused. Basically the equation used is σ=M/Sx I know what σ and M are, but I haven't a clue what Sx is...

Thanks for your response! Do you have an idea by how much the coil surface temperature rises? If the air temperature increases by 300 F does the surface temperature of the coil also increase by 300 F or is it a different proportion? When you say you can raise the temperature by adding more...

I'm curious how heat transfers between the heating element in my electric oven and the air in the oven. Say when I first turn on my oven the air is at room temperature (say 70F) and the surface temperature of the heating coil is at say 500F. After some time passes, the air in the oven rises...

Homework Statement How far above the surface of the Earth do you need to be for the force of gravity to be reduced to 70% of its value on the surface. Homework Equations g on surface is 9.8 m/s^2 Fg=G*m1*m2/r^2 The Attempt at a Solution Is there a way to do this without...

Homework Statement I have three valve/coil systems connected in parallel as shown in the attached figure. If I know the head loss of each valve/coil is 40 feet, can I add them in parallel like you do with resistors in circuits? Thanks! Homework Equations 1/h=1/h1+1/h2+1/h3 (possibly)...

Thanks Simon, I wouldn't have thought of that :).

Hi, I'm designing the attached aquaponic system and am trying to estimate the speed at which water will drain through the pipes. Basically, water enters the top of the pipe, then drains through roughly 5 feet of soil before it exits the pipe. Is there a way to estimate the speed at which the...

It sounds like its not understanding your data since it says the size is [0,0] when it should be [500,8]. Could you attach the code?

Out of curiosity, is there a fundamental reason why a pump that can pump 200 gph to a height of 5 feet, can't also pump 100 gph to a height of 10 feet?

Fascinating. Fluid mechanics has always baffled me. Thanks!