OCR Physics A G484 - The Newtonian World - 11th June 2015

Another thing to check, do we draw the gravitational field lines into a planet? Or just to its surface?

Another thing to check, do we draw the gravitational field lines into a planet? Or just to its surface?

I'm going to guess you have got geostationary and polar the wrong way round, but if not.

What use is a satellite that is staying above the same point on earth, it would be far too expensive and impractical to move it everytime the spy target changes, a polar orbit would be far superior, as it can easily cover the surface of the earth in a number of orbits.

Communication satellites are normally geostationary, as it makes it easier to point the antenna towards it, Otherwise everybodies sky dish would have to move constantly so it is always pointing towards the nearest satellite

january 2014 question 3cii ? i don't get what they done they worked out the gradient then how did they get 5.7hz or something like

I've just had OCR for Chem 4, really bad exam! Plus the AS units were apparantly really different. Prepare yourselves guys, I've got a bad feeling about this one

I have question about when do keep you answer, for the next question. For example if you out the answer in part (i) to be 7374.48729 and round to 3.s.f. (7370) and then in part (ii) it asks you to find something using that answer which one do I use 7374.48729 or 7370

january 2014 question 3cii ? i don't get what they done they worked out the gradient then how did they get 5.7hz or something like

Its june 2014 and to get f you use the formula

a = -(2pief)^2 x which is in the formula book
the gradient would be acceleration over displacement in that graph so a/x, so pick one value for a and x then

using formula the a/x (which is the gradient) = (2pief)^2

now you solve for f

So basically you just pick a value of a and x from the graph to use in the formula and a/x happens to be the gradient

How are you guys feeling about this one. I feel like it's easy to f*** it up since a small difference in marks will have a big effect on your grade.

I've dont all of the 2014-2010 past papers about 3 times each, been getting 50-60 marks but I'm still scared some word question will throw me off or im gonna forget to convert km to m for example, but my biggest worry is time. Time is my biggest enemy, I don't even know what the point is of having such a tight time limit, make it 1hr 45min or something so everyone can attempt each question with no problem...

As someone who actually sat both g481 and g482 I can tell you that the papers weren't at all that different. G481 was still a walk in the park, slightly less definitions than usual was all, and g482 was no different than last year. If you understand all the topics then you will be fine. After every exam people come out of it saying how different it was and how impossibly hard it was, invariably they're the ones who haven't done that much work and are laying down the foundations of their excuses!

Well it would depend on the kind of spying, if you wanted to take pictures of the same place at different time intervals then a geostationary orbit would be better for this. If you wanted to take pictures of the whole world then a non-geostationary orbit would be better.

G481 2015 wasn't that different....

I think it would be very risky to put down a spy satellite for an example of geostationary satellites. Sure they may exist, but they are probably just used as relays, and not imaging in the traditional sense.
It would be much safer to put down spy satellites as having non gso orbits, as this allows them to cover the whole earth fairly regularly. (I think there may have been a g481 question on this a few years back).

I'd probably avoid spy satellites all together really.

I thought it was completely unlike any other g481 paper I'd ever seen.

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Yeah I would agree I would always put weather or communications to be on the safe side.

I think it would be very risky to put down a spy satellite for an example of geostationary satellites. Sure they may exist, but they are probably just used as relays, and not imaging in the traditional sense.
It would be much safer to put down spy satellites as having non gso orbits, as this allows them to cover the whole earth fairly regularly. (I think there may have been a g481 question on this a few years back).

I'd probably avoid spy satellites all together really.

eeggh I feel like with OCR your grade is like 20% luck of the mark scheme. Answers vary for pretty much the same question, and sometimes you can put perfectly relevant and correct physics which answers the question but you won't get any marks because you didn't put the exact phrasing they wanted. It's got such a gcse memorise-it-rather-than-understand-it vibe