zakfab

Is this question all way over your heads or something??

Surely you come acroos this all the time when you mess up a calculation slightly.

Is it possible to do the inverse Laplace Transform of a constant?

I ask because I have a differential equation which I transformed, solved and now need to find the invers of. Unfortunatly my answer has a constant, and I don't know what to do about it!!!

Thanks!

It has a lot to do with the colouring in the drinks, and what other chemicals are in it to make it taste better.

If you drink vodka straight, or with water, you shouldn't get a hangover!

Current is the flow of charge. Just one electron moving throughout a conductor is a flow of charge, so it would be classed as 'electricity'.

The guy wants to know how to check his sum. He downloaded his program, along with his checksum.

Now how does he compare the checksum he downloaded with the program?

Science of mind is what brings that which cannot be named, because structure hinders the studier from comprehending the mind in it's true state, as opposed to a bag of satsumas.5 kilos and assorted nuts and bolts which only hinder Anna Kournikova from showing her true fiendish, but perfectly shaped

I got help elsewhere when the forum went down, thanks anyway!

I wish I knew!

The lab was about characteristics of DC motors, comparing torque with armature current/voltage (don't ask me what armature is!) and speed in rads per second.

I have to derive the equation E = K(phi)(omega) using Faraday's Law, which i believe is E = -N(d(phi)/dt)

All the other stuff I wrote was trying to explain what I meant in the equations because I don't know how to do symbols on here.

I have just done a bit about DC motors in a lab, and now i have to derive the equation:

E = K(fi)(omega)

E = back emf

K = Z/(2(pi) where z = number of conductors carrying current, I

(fi) = magnetic flux

(omega) = angular velocity of motor (rad/s)

So I have to derive that from Faraday's Law, which I assume means:

E = -N(d(fi)/dt)

N = number of turns of a coil

t = time?

I don't have a clue where to start! Someone pleeese help ASAP!

I read catcher in the rye a few years abo when I was about 16, I can't imagine how dull it would be to actually STUDY it.

Whenever we studied a book in school it totally ruined it!

I'm reading 'Persuader' - Lee Child

and 'In search of Schrodingers cat' - john Gribbin

In Southampton they set off fireworks every night from about October 1st until New Year. Kids eh? I wouldn't be suprised if one kid a week ends up needing hospital treatment for firework related injuried just here!

Haha, can't wait for faf's next reply

Kedas: Could you elaborate on how you got the r cos (theta) parts, and how you know to multiply by F/E?

Thanks

Does anyone know any software which will create a graph of stress/strain from a table of stress and strain values?

Whenever I try with Excel it puts stress as one axis, then plots strain as a line on the graph.

Can someone either tell me how to use excel or give me another good graphing program?

Thanks.

We need to know more about your plan to see if it will work or not.

But if you tell us it surely won't work because we will be able to counter it!

I swear we have never done this in class.

Thanks Kedas I'm gonna have to totally analyse your answer

Another question, which means I'm stuck again, lol.

A 60mm diameter sphere, with modulus of elasticity E, has parallel flats on it 20mm each side of the central axis. If a compressive load F is applied perpendicular to the flats, demonstrate the decrease in length along the loading axis is given by:

2F            0.73rad                  d(theta)
--------      (integral sign)        ----------
r*pi*E         0                        cos (theta)

Where (theta) is the angle between the central axis and any point along the surface of the sphere, and r the radius of the sphere.

looks like this:

____

(____)

I hope you get that :S

I used Avant for a while, but moved back to Opera, It's definatley the best browser.

I thought Avant was better than MYIE2 (and a load of others I tried)

Go with Opera AND Avant, you willl need Avant for the stupid sites that only work with IE

So you are supposed to know the modulus if it says the material?

I will have to remember that!

I thought I should use the diameter to work out the cross sectional area and so something with that.

Tension is just force right?

if I use strain = change in length/original length

strain = 1/1524

Then if I knew Young's Modulus or something I could work out stress, then work it out with the cross sectional area (3.167*10^-5) * the stress.

Alas, no Young's Modulus, so then I'm stuck.

I think I will just presume the question was supposed to include Young's Modulus for steel for the moment. E = 207 * 10^9 N/m^2

It works that way.

If anyone can do it with just the original information please tell me how!

This is a homework question, it doen't have to be handed in, so there is no rush to answer, but the question has totally confused me!

A steel bolt has a diameter of 6.35mm and a single start thread of pitch 1mm. The bolt is used to fasten together parts of a machine.When the parts are just in contact, without load on the bolt, the distance betwee the bolt head and the nut is 254mm. Estimate the tension in te bolt if the nut is tightened by 1/6 of a turn. State your assumptions. Would you expect your result to be larger or smaller than the actual load? Why?

The answer is 4.3KN, larger.

Any pointers/or a method would be greatly appreciated!

Cowboy bebop is brillian, but Ed is weird

I am doing electromechanical engineering at Southampton in October.

I got A for Maths, B for physics, B for chemistry.

Last year i got straight A's, really high, this year i got mostly C's and couple of B's and a D... what went wrong?! lol. Got into my course anyway, they wanted AAB, but let me in

I have been using Avant for ages, Its much better than all the other skins (better thn MYIE etc)

Opera is good aswell, but it has averts, so Avant is the way to go