# Recent content by question dude

1. ### Showing a vector field is imcompressible

Do I treat the non-bold r as a constant? If sub in bold r, I get: G = [(x^2 + y^2 + z^2)^0.5 ] / 4*pi*r^3
2. ### Showing a vector field is imcompressible

Homework Statement Homework Equations The Attempt at a Solution As you can see, the solution is shown just below the question. Essentially, I don't understand how the x, y and z component of the vector field has been separated because the numerator of the vector field's fraction is: (x^2...
3. ### How to work out expected frequency from normal distribution

How is the expected frequency column worked out for each interval of trains? 2) My attempt Take the first interval, 60 - 62, I thought about doing this: (62 - mean) / standard deviation (62 - 67.45) / 2.92 = - 1.866 using Z score < - 1.886, from the normal distribution table, I get: 1 -...
4. ### Determining the forces in a framework

The framework is attached below. I've tried going to each joint and resolving the forces vertically and horizontally. I've got to joint B and I'm stuck, because I have three unknown members there. And its the same if I go to joint J. what do I do?
5. ### Ground water flow question

'head' is simply stress (or pressure) mulitplied by depth for total head is the total pressure as it were
6. ### Ground water flow question

Its attached below. I don't understand how you work out the total head. Can someone explain how you do it? I'm really struggling. I know how to do the elevation, which is just the height above/below the datum level. And I've checked the solutions as well, it seems like you're supposed to work...
7. ### Determining forces in members of a structure

Theres no rebuilding, I've built the thing, and now I've got to analyze it as it is (terrible situation I admit). The whole structure is supported at its two ends. One is shown on left of my diagram, hence there is a 4KN arrow, and the other is the right hand side of the structure which isn't...
8. ### Determining forces in members of a structure

This is actually half pf a complete structure (which I have designed and built), so I have omitted the rest of the right hand part in my diagram, but lets assume that we know the forces in the other members (caused by the applied loads). What I want to ask is, whether theres a way to work out...
9. ### Determining forces in members of a structure

Homework Statement I want to find the force in the vertical purple member. Assuming I know the forces in all the other members, theres a problem with working out the force in the purple member. (Bear in mind, I'm using the method where I assume equilibrium at each joint in the...
10. ### Directional derivative question

Sorry about that, what I meant to get across, was that I understood the method in a sort of algorithmic way, but didn't understood the reason behind steps due to not understanding some basic stuff like 'level curve'. Anyway its sorted now.
11. ### Directional derivative question

Thanks a lot!!! I understand whats going on now. Before I was just plugging in the numbers without knowing the concepts properly.
12. ### Directional derivative question

I've done the first part, but I'm stuck on the second paragraph of the question. Maybe I'm being stupid, I don't even understand exactly what is meant by, 'the level curve'. I also don't quite understand the whole concept of directional derivative. When it says, 'the gradient in the...
13. ### Use of guassian elimination to find the determinate of a matrix

the matrix I posted in the pic inb my 1st post was for matrix A, not (A - I*lamda) I've done what you've suggested, by writing down A - I*lamda, its basically the same as matrix A, except for the three values in the central diagonal, they each have '- lamda' I'm trying to calculate the...
14. ### Use of guassian elimination to find the determinate of a matrix

seems like a decent method, never come across it before though is there any significance to the values next to each of 'a' in the matrix shown in your first link?
15. ### Use of guassian elimination to find the determinate of a matrix

but theres two values in row 3 that I need to get to zero I can't make a subtraction that would get them both to zero, because they're not the same values sorry I can't see why