Supergrunch Posted June 4, 2007 Share Posted June 4, 2007 It's all about remembering the difference of two squares, it also becomes useful for imaginary numbers (getting i's to the top) and simplifying nasty functions of cos, sin, cosh and sinh. And you can use sum of two squares as well with imaginary numbers. eg. x² + y² = (x + yi)(x - yi) Not that it's as useful... Link to comment Share on other sites More sharing options...
Nucleus Posted June 24, 2007 Share Posted June 24, 2007 Last GCSE tommorow - Physics Seperate Science. I'm looking at a past paper and cannot for the life of me figure out this question: The mass of the satellite is 1000kg. Calculate its weight in this orbit. Any ideas? edit: Oh, its a geostationary satellite so it takes 24 hours to fully orbit the globe. Link to comment Share on other sites More sharing options...
chairdriver Posted June 24, 2007 Share Posted June 24, 2007 Is it not just 1000Kg x 10 (or 9.8 if you are picky)? So the answer would be 10,000 N. Link to comment Share on other sites More sharing options...
Nucleus Posted June 24, 2007 Share Posted June 24, 2007 I'm such a retard. I was reading the wrong question . Sorry, my desk is covered in sheets. The question was - "The geostationary orbit is at a radius of 424000 km. Calculate the centripetal acceleration for this orbit". Link to comment Share on other sites More sharing options...
chairdriver Posted June 24, 2007 Share Posted June 24, 2007 I'm such a retard. I was reading the wrong question . Sorry, my desk is covered in sheets. The question was - "The geostationary orbit is at a radius of 424000 km. Calculate the centripetal acceleration for this orbit". Thats a GCSE question?!? Shit, I'm going to do badly tommorrow... Link to comment Share on other sites More sharing options...
Twozzok Posted June 25, 2007 Share Posted June 25, 2007 haha GCSE's. Trust, compared to As/2 GCSE's are total piss. (Not that I know what the fuck that question is on about :P) Link to comment Share on other sites More sharing options...
Letty Posted June 27, 2007 Share Posted June 27, 2007 Anybody fancy describing how CCD's work to me in laymans terms? Wikipedia has left me baffled. Also, are devices with 3CCD's analogue? :s Link to comment Share on other sites More sharing options...
Konfucius Posted June 28, 2007 Share Posted June 28, 2007 Also, are devices with 3CCD's analogue? :s No I think anything with a CCD is digital. Most devices have three CCDs. A CCD is a light sensor. Visible light consists of red, blue and green. Therefore there are 3 CCDs, one for each colour. I'm not sure how to explain it properly but I'll try: Let's take a LCD monitor for instance. It has a set amount of pixels, for instance mine is 1280*1024 which is about 1.3 Megapixels (you surely are familiar with this term in digital cameras). Now each of these pixels has three transistors (red, green, blue) so that the pixel can take any colour. The CCD is basically the same but the other way round, it doesn't emit light but rather absorbs it - as previouly said it's a sensor. And to be able to store a colour picture on your digital camera you need three of those. One for each colour. If you have photoshop open a colour picture and then go to the channels tab (normally next to the layers) and de- and reactivate some of the channels, that should give you a good idea how this works. Hope that helped. Link to comment Share on other sites More sharing options...
Letty Posted August 30, 2007 Share Posted August 30, 2007 If anyone can answer this before 12:05, they get a prize. Using 8 bit two's compliment, how would I represent the binary number -120? When I get an answer, it is always 00000000 : / Link to comment Share on other sites More sharing options...
Mr_Odwin Posted August 30, 2007 Share Posted August 30, 2007 1111000 (I think.) The cheaters way to do it is to load up Window's calculator, put it in scientific mode, type in your number then change the mode to binary. Edit: Actually maybe there should be a leading one too: 11111000 I dunno ... Edit2: Changed my mind again (just noticed it was -120): 10001000 Link to comment Share on other sites More sharing options...
Letty Posted August 30, 2007 Share Posted August 30, 2007 1111000 (I think.) The cheaters way to do it is to load up Window's calculator, put it in scientific mode, type in your number then change the mode to binary. Theres only 7 characters there :s But yes, I know you can use a calculater, but it only gives you the signed bit answer afaik Link to comment Share on other sites More sharing options...
Mr_Odwin Posted August 30, 2007 Share Posted August 30, 2007 I think my Edit2 is right. As it's negative there is a leading one. The remaining seven digits of the represent 8 as -128+8=-120, as required. Never come across this stuff before. Wikipedia to the rescue. Link to comment Share on other sites More sharing options...
Charlie Posted August 30, 2007 Share Posted August 30, 2007 If there are only 7 characters add an extra 0 on at the beginning of the number. 01111000 Two's compliment is a bitch. from what I remember of Higher Computing. Get the number into normal binary, then switch the 1s to 0s and vice-versa, then add a 1. Link to comment Share on other sites More sharing options...
Ginger_Chris Posted August 30, 2007 Share Posted August 30, 2007 I was wondering when this thread would be revived. I have a purpose on the boards again :P Link to comment Share on other sites More sharing options...
Supergrunch Posted August 30, 2007 Share Posted August 30, 2007 I was wondering when this thread would be revived. I have a purpose on the boards again :P You and me both. I was going to bump it for the new school year. (has that started yet?) Link to comment Share on other sites More sharing options...
Strider Posted August 30, 2007 Share Posted August 30, 2007 (has that started yet?) Well i start 6th form next tuesday, so i guess everything kicks off then. Link to comment Share on other sites More sharing options...
Ginger_Chris Posted August 30, 2007 Share Posted August 30, 2007 I hope not, I've got to start organising a orientation placement in a school as soon as their term starts. Plenty of time until the 8th right? Link to comment Share on other sites More sharing options...
Letty Posted August 30, 2007 Share Posted August 30, 2007 If there are only 7 characters add an extra 0 on at the beginning of the number. 01111000 Two's compliment is a bitch. from what I remember of Higher Computing. Get the number into normal binary, then switch the 1s to 0s and vice-versa, then add a 1. Thats the theroy, but whenever I try, I always end up with 00000000 : / thanks odwin Link to comment Share on other sites More sharing options...
mariosmentor Posted August 31, 2007 Share Posted August 31, 2007 I need to come up with a treatment and synopsis for a 4 minute factual documentary dealing with issues affecting modern Glasgow for a Ch 4 short slot. I'm away to a festival tomorrow morning so if you can have it done by Monday and PM me it that'll be great. Also no pressure...but if it's no good then I'm not accepted into Second year. good luck candidates..... Joking! But still I should get started :P Link to comment Share on other sites More sharing options...
Fanelia Posted September 2, 2007 Share Posted September 2, 2007 has anybody got a paper on the cultural influence of elvis presley? that would be great. Link to comment Share on other sites More sharing options...
Ginger_Chris Posted September 2, 2007 Share Posted September 2, 2007 http://en.wikipedia.org/wiki/Elvis_Presley_phenomenon Not the article itself but the references at the bottom, with a bit of tracking down, may be fairly useful. Wikipedia is always a decent first stop for finding preliminary references. Link to comment Share on other sites More sharing options...
Fanelia Posted September 2, 2007 Share Posted September 2, 2007 holy cow, that's great help, chris. i'm serious. i wikied already on just "elvis" but the biographical material wasn't what i needed. thanks a lot. guess i have much to learn about wiki. Link to comment Share on other sites More sharing options...
Strider Posted September 13, 2007 Share Posted September 13, 2007 Revived Anyway. I need help with some evil surds and i know there are some very good maths people. Simplify: (Root 2 - 1 ) (Root 2 + 1) I got Root 2 + 1, but knowing me i'll be wrong. So any help would be great please Link to comment Share on other sites More sharing options...
Ellmeister Posted September 13, 2007 Share Posted September 13, 2007 Revived Anyway. I need help with some evil surds and i know there are some very good maths people. Simplify: (Root 2 - 1 ) (Root 2 + 1) I got Root 2 + 1, but knowing me i'll be wrong. So any help would be great please I got the answer as 1.. root 2 x root 2=2 then root 2 x +1= +root 2 then root 2 x -1 = -root 2 meaning the root 2 cancel out. then +1 x-1=-1 therefore 2-1=1 1! but I'm probably wrong Link to comment Share on other sites More sharing options...
The fish Posted September 13, 2007 Share Posted September 13, 2007 Revived Anyway. I need help with some evil surds and i know there are some very good maths people. Simplify: (Root 2 - 1 ) (Root 2 + 1) I got Root 2 + 1, but knowing me i'll be wrong. So any help would be great please (Root 2 - 1 ) (Root 2 + 1) gives you 2 - Root 2 + Root 2 -1, which equals 1. Explanation: Root 2 x Root 2 = 2 Root 2 x -1 = - Root 2 Root 2 x 1 = Root 2 1 x -1 = -1 Put simply, the answer is 1. Link to comment Share on other sites More sharing options...
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