# Search results

1. ### How to determine force using a measured current

I don't think I can show you a diagram, but I can try to explain it better: I am applying force to a lorentz force motor which has a displacement transducer in it which produces a change in current when the height of the motor increases and decreases (you put your foot onto the plate of the...
2. ### How to determine force using a measured current

Hi, I'm trying to calibrate a voltage divider circuit to measure force. I have measured the current output at two different weights, converted the weights to forces using "f=mg" and calulated a gradient from that using "y = mx + c" as well as the constant. However, I don't feel what I did...
3. ### Applying Bernoulli's equation to magnetohydrodynamic flow

1. Homework Statement A static electrically conducting fluid, in the presence of electric and magnetic fields, experiences a Lorentz force. Determine the fluid pressure at point (1,2,1) when the pressure LaTeX Code: p_{0} at origin (0,0,0) is under the effect of gravity and the electric and...
4. ### Applying Bernoulli's equation to magnetohydrodynamic flow

Homework Statement A static electrically conducting fluid, in the presence of electric and magnetic fields, experiences a Lorentz force. Determine the fluid pressure at point (1,2,1) when the pressure p_{0} at origin (0,0,0) is under the effect of gravity and the electric and magnetic field...
5. ### Proving tensor symmetry under transformation

Did I not write my question properly or does no one know?
6. ### Proving tensor symmetry under transformation

Homework Statement Using indical notation, prove that a 2nd order symmetric tensor D remains symmetric when transformed into any other coordinate system. Homework Equations Tensor law of transformation (2nd order): D'_{pq} = a_{pr}a_{qs}D_{rs} The Attempt at a Solution I think I'm...

Anyone?
8. ### Proof of transformational symmetry

Homework Statement Using indical notation, prove that D retains it's symmetry when transformed into any other coordinate system, i.e. D'_{pq} = D'_{qp} (where D is a symmetric 2nd order tensor) Homework Equations D'_{pq} = a_{pr}a_{qs}D_{rs} (law of transformation for 2nd order tensors)...
9. ### Kronecker Delta

Homework Statement Simplify/Evaluate these expressions involving the Kronecker delta, using Einstein's summation convention: a)\delta_{qr}\delta_{rp}\delta_{pq} b)\delta_{pp}\delta_{qr}\delta_{rq} Homework Equations \delta_{ij}=0 when i =/= j \delta_{ij}=1 when i = j The Attempt at...
10. ### Orthogonality of Sine and Cosine functions

Hi, would anyone be able to explain how to evaluate a function using orthogonality (i.e. using orthogonality to solve a definite integration problem with sines/cosines)? Thank you
11. ### Partial Differential Equation using separation of variables

Homework Statement Solve the heat flow problem using the method of separation of variables: Homework Equations PDE:\frac{\partial u}{\partial t}=k\frac{\partial^{2} u}{\partial t^{2}} for 0<x<L, 0<t<\infty BC's:\frac{\partial u}{\partial x}(0,t)=0,\frac{\partial u}{\partial x}(L,t)=0...
12. ### Partial Differential Equations Question

Hi Cyosis, I did make a mistake while equating. Thank you :)
13. ### Partial Differential Equations Question

Hi, do you mean try solving \frac{\partial^{2} u}{\partial x^{2}}=2\frac{\partial u}{\partial t} without substituting u, first? Thanks
14. ### Partial Differential Equations Question

Homework Statement Find the link between constants \omega and \beta so that http://www4e.wolframalpha.com/Calculate/MSP/MSP181963g2e5f4i43d3b00005ief8e24920ah323?MSPStoreType=image/gif&s=20 [Broken] is a solution of \frac{\partial^{2} u}{\partial x^{2}}=2\frac{\partial u}{\partial t} (A...
15. ### The path of crossing a stream

Hi, was the hypotenuse correct? Because if I did it via Pythagoras, it yields an equation which I do not think is equal. \sqrt{(W-x)^{2}+y^{2}}
16. ### Introduction to Algebra

This isn't physics. I suggest you post here next time: https://www.physicsforums.com/forumdisplay.php?f=155 1/-2 is the same as -1/2, so generally you just put the negative sign in front of the numerator.
17. ### The path of crossing a stream

I think this diagram is more accurate than my previous one. (See attached figure)
18. ### The path of crossing a stream

How about this? (See attached figure) Thanks
19. ### The path of crossing a stream

Do you mean like this? (See attached figure.) Wouldn't the initial position be (0,0)? Thanks
20. ### The path of crossing a stream

Sorry, yes the watercraft does always point towards the pier (throughout the journey). Please see the attached figure for a more representative diagram. What do you mean by choosing an origin? Thanks
21. ### The path of crossing a stream

Homework Statement A watercraft is crossing the stream to reach the pier. (See attached figure.) Basically, I have to derive an ordinary differential equation of the path the watercraft travels, which I can then solve using MatLab, etc. i.e. derive \frac{dy}{dx} in terms of V_{W}, V_{B}...
22. ### Integration of an inverse sqrt composite function

Unfortunately not very familiar at all. I haven't really dealt with composite integrals. But I'll try: a = g.z b = (mB.g)/u 1/(a+bz)^(1/2) v=(a+bz), so dv=b*dz. This turns the integral into 1/v^(1/2)*dv*(1/b). Integrating v^(-1/2). So:- Integration: ....f L t= | (1/(([g.z] +...
23. ### Integration of an inverse sqrt composite function

Ok, I was trying to use the chain rule lol >< So:- Integration: ....f L t= | (1/(([g.z] + [(mB.g)/u])^(1/2)).dz ....j 0 ....f L t= | 2.([(g.z^2)/2] + [(mB.g.z)/u] + C)^(1/2) ....j 0 Where: mB = mass of box mR = mass of rope g = 9.8 ms^2 z = 77.0 m How am I doing...
24. ### Integration of an inverse sqrt composite function

Oh, ok. Thanks for pointing that out :) So:- u = mR/L = mR/77 T(z) = u.z.g + mB.g v(z) = (T(z)/u)^(1/2) dt=dz/v(z) z = the length of the rope = L (used for integrating) The Attempt at a Solution v(z) = (T(z)/u)^(1/2) v(z) = ((u.z.g + mB.g)/u)^(1/2) v(z) = ([(u.z.g)/u] + [(mB.g)/u])^(1/2)...
25. ### Integration of an inverse sqrt composite function

Hi Dick, z is the length of the rope (77.0m as in the problem) it was just the letter they used in the formula sheet so I carried it forth. How was my integration? I don't think I know how to integrate nested functions (I assume it's something like the reverse of the chain-rule?).
26. ### Integration of an inverse sqrt composite function

Homework Statement “Geologist A” at the bottom of a cave signals to his colleague “Geologist B” at the surface by pushing a 11.0 kg box of samples from side to side. This causes a transverse wave to propagate up the 77.0 m rope. The total mass of the rope is 14.0 kg. Take g = 9.8 m/s². How...
27. ### Unit of the Determinant of a 2-space Matrix

No units, it just says calculate the area of N.M and calculate det(N). I just want to cover my bases as it asked for area and I thought I should just put a unit of 'units^2' at the end...
28. ### Unit of the Determinant of a 2-space Matrix

Well, yeah. Finding the area of a unit square 'ABCD' that is represented by a 2x4 M matrix = [ 0 1 1 0 ] [ 1 1 0 0 ] which has been multiplied by a 2x2 matrix N = [ -2 0 ] [ 0 -2 ] I had to calculate the area of N.M and the determinant of the N matrix. And I was just wondering since...
29. ### Unit of the Determinant of a 2-space Matrix

Do determinants of a 2-space matrix have a unit of [units]^2? Also, does A_parallelogram = || u x v|| have a unit of [units]^2 too? This has confused me as Area has a unit of [units]^ 2 but the examples from the Contemporary Linear Algebra (Anton and Busby) text book does not state any units...
30. ### Max. velocity with given coefficient of static friction (μ_s)

I did draw a diagram originally to get part a of the question and it was right. The only thing that has changed is that they gave me a coefficient of static friction. It should be the same diagram still since the angle of 23.5 degrees still applies... I got two questions from it (the x and y...