Biggz

For my Engineering Mechanics lecture i have been tasked with designing a hollow circular shaft. I have calculated that the shaft will have a maximum shear stress of 434.35MPa using equation

T/J = GO/L = t/r

Where T = torque, J = second moment of area, G = shear modulus, O = angle of twist, L = length, t = shear stress and r = radius

Now i have my value i assume i need to choose a material that can withstand a shear stress greater than 434.35MPa but i cant find a data table to find the shear values.

Is there some way to workout shear stress?

Can i simply assume that if a material has a yield strength of, say, 500MPa it would be suitable?

need help understanding where this answer comes from if anyone can explain i would be very grateful.

Q) determine and then sketch, the time domain response, y(t), for the following transfer function, T(s), and its input r(t).

T(s) = 3/(s+3) ; r(t) = u(t)

The answer is given as y = (1-e^-3t)

I get the inverse laplace of T(s) to be 3e^-3t and im assuming that u(t) refers to the input being a step input but i cant see how the answer given is y=(1-e^-3t)

If someone can explain id be grateful.

For my uni assignment i have to design a hollow circular shaft that can withstand 37,000kW at 100 rpm. (calculated this to be 3.53MPa of torque)

the specification of the shaft are as follows:

-the shaft length should be 20 times the external diameter, D.

-the ratio of external diameter, D, to internal diameter, d, should be 7:3

-the thickness of the shaft should be 100mm

I can chose the material but im struggling to find the size of the shaft.

I know that t=0.1m and t=D-d but the ratios is throwing me off. Do i need to convert either the external or internal to the other so i have the equation in terms of all internal or external? or can i simply call the unknown value x and say that D = 7x and d = 3x?

I'm really at a loss here, i think i might be making this harder than it needs to be but if anyone can tell me how to find the external and internal diameter i would be very appreciative.

This may end up a bit long but please stick with it.

I've been seeing this girl casually for a few months; we have gone on a some dates and we hang out some times but we are both quite busy so its not easy. When i text her just for a chat she takes a long time to reply (usually about an hour but sometimes longer) though i have noticed that when i text to ask her out she replies really quickly. I always pay when we go out though she has offered.

At the end of the dates i look to kiss her but she seems quite reluctant though she did kiss me when we were both a bit drunk, i told her that i liked her and she said the same, and we hold hands quite a bit.

I asked her to be my valentine earlier this year and she said yes and we went out for a meal. At the end of the night i walked her home and tried to kiss her but she turned away, though we were at her parents.

The conclusions i have come to are that she is either: really shy, though she doesnt seem it, likes me but is playing hard to get or else she is just stringing me along until she gets a better offer.

Let me know what you think please.

Ok so this morning i woke up to find that a package had been delivered to me, since i was expecting a package (late christmas present) i didn't think it unusual. I opened the package and instead of being the christmas present it was a router with cables and card telling me the settings for the router.

It has an set-up guide from talktalk but my ISP is Virgin media and i have never been on talktalk. I really have no idea how or why this router has come to me but i was wondering what i should do with it? I don't need a router, could it possibly be a scam? I don't think there is a return address on the box and i will check my bank shortly to see if any money has gone out for it.

Any advice would be appreciated.

I met this girl a couple of days ago while on a night out and got to talking to her (we were both outside the club and she was cold so i gave her my top) anyways she added me on facebook so i messaged her and we were getting on well.

I gave her my number and said drop me a text, we should go out for a drink sometime. She texted me and she always ended her texts with an x and a :) so i asked her if she fancied going for a drink the next night and she said "yh if i aint doing anything i'll have to let you know :) x"

So i text her today and she hasnt text me back yet (its been about 5 hours) i know that she is very busy (she is a nursing student and works in a hospital) but i dont know if she was just being polite and that saying she might be busy was her way of saying no or maybe i am just being stupid.

opinions?

Im looking at getting a motorbike and i have heard that chinese bikes are very unreliable and that they have no parts back up. I know the best bikes to get are either Japanese or European and that most people would rate a 10-15 year old honda better than a brand new chinese bike but my question is; would a brand new Chinese bike that has a good parts back-up and a 3 year warranty be a better option than an old japanese bike. The warranty is what makes me think its not such a bad deal and its cheaper for the chinese bike new than it is for an older honda, suzuki, yamaha etc..

I have ginger hair, it is not that ginger and i dont have lots of freckles but my hair is definately ginger, i was just wondering what most womens opinion of ginger hair on a guy was cuz it seems that most people dont like it.

Whenever I do frenchpress (skull crusher), tricep extensions or dumbbell curls I get pain in my forearms which usually causes me to stop a set due to the pain; my forearms give out before anything else. My form is good and I'm not using too much weight but the pain persists. Has anyone else had this problem and how did you deal with it?

I'm in the process of writing a song and I've come to the part where I want to put a solo. The chords are Fmaj Am Gmaj Gmaj. I tries using F major but it doesn't right. Thanks in advance

This is mainly aimed at women but it goes for men as well. If a person is fat but they are a great person, they are good looking and are intelligent does any of that matter? It seems that every guy that women consider hot is a total douche. So my question is can you look past a persons weight or does it immediatly mean you cannot like that person?

Hi i am 17 now and i have always had trouble with my writing skills. It has not affected my intelligence at all, i am currently studying A2 math, physics and chemistry. Today i was talking to a friend and somehow we got onto the subject of writing and after a while discussing it she said i might have dysgraphia, which i didn't know but she has.

I'm always putting capitals in the middle of words even though i know its wrong i still do it anyway. I'm always spelling words wrong even when copying off the board or out of a book. My entire arm aches after only writing small amounts. I have cross-dominance (ie i write right handed but i play cricket left handed, i'm left footed, i play tennis right handed and golf left handed and i play guitar right handed and i'm a southpaw boxer) also When i was younger i used to mix up my b's and d's.

So my question is am i dysgraphic? If yes what can i do for it.

I recently bought a Peavey Vypyr 15 from my local music store which they said was a returned item that had been repaired in store. When i first turned it on for an in-store test there was a very loud squeel but when the guy turned it down and took off the tube screamer it went ok and sounded decent so i bought it. The Cable they supplied me with doesn't seem like it goes with the amp (it is shaped at a right angle where the cable is bent out of shape by the amp frame) and the cable says 10A, 250V. When i first turn the amp on to use it there is a loud pop, the clean channels are distorted and if i turn it above 1-2 volume the sound becomes unbearable (really muddy).

The Speaker in the amp is 3 ohms 25 watt and i dont know whether this is right or if they have replaced the original speaker and the aux in port worked for a while but now gives me a tonne of feedback and wont play music when plugged in.

My questions are: Can anyone tell what is wrong from the amp from that information?

Is this amp any good when it is new? ie: are all vypyr 15s shoddy?

Shall i return it (they gave me a years guarentee)?

Someone was telling me about a day when they want everyone to turn everything off for an hour as a campaign for the "fight against climate change". I have never believed global warming but i can't honestly believe how bad things have got. People have openly accepted the theory that a) CO2 is some sort of killer gas that causes the Earth's temperature to increase, and b) Human activity actually directly or indirectly affects climate.

So i wanted to see for myself how many people believe in Man-made global warming and why they do.

I found some music i like on youtube and i was looking to find some more in a similar style so can someone please tell me what this is?

http://www.youtube.com/watch?v=03dJHrLdVl0

Thanks

I don't actually cough up blood but when i do cough it tastes like blood.

I am slightly over weight but not a lot and i dont smoke but some of my familly do. Does anyone have any ideas?

In the production of sulphuric acid, sulphur dioxide is converted to sulphur trioxide by reaction with the oxygen in the air. What volume of air (assuming 20% of the air is oxygen) would be needed to produce 150cm3 of sulphur trioxide? Assume complete conversion of sulphur dioxide to sulphur trioxide.

Can someone help me with this question and tell me how to work it out please.

3) solve the following equation by:

i Completing the square.

ii using the formula.

5x^2 +3x - 1 = 0

i recently downloaded a file and because i am not the admin on my computer (vista) i have to press run as admin and enter the password. so i pressed don't run because i thought i could find the file and run as admin but when i went to find the file i could not find it so i did a search and it said it there was no file.

has anyone got any suggestions because i really dont want to have to download it Again