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OCR MEI M1 9th June 2015 4761/01

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Original post by lizard54142
One would clearly be vertical, but would the other section be straight?


not too sure :frown:
Original post by docdoc02
i thought there might be a simpler way as its 3 marks and the one before that was more :/


You would but I guess maybe the angles are easy to work out.
That's the way I'd do it anyway:tongue:

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Original post by docdoc02
not too sure :frown:


The 0.5m length would be vertical, but the 2.3m length would be slacked, because the distance CB is 22+0.52\sqrt{2^2 + 0.5^2}, assuming AC is 0.5m. CB < 2.3m... can you finish?
(edited 8 years ago)
Original post by Leechayy
You would but I guess maybe the angles are easy to work out.
That's the way I'd do it anyway:tongue:

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You can in fact do it without any calculations.
Do you need to know the projectiles general equations?
Original post by lizard54142
The 0.5m length would be vertical, but the 2.3m length would be slacked, because the distance CB is 22+0.52\sqrt{2^2 + 0.5^2}, assuming AC is 0.5m. CB < 2.3m... can you finish?


if something is slack does that mean it has no tension in it?
Original post by docdoc02
if something is slack does that mean it has no tension in it?


Yes
Original post by bd17
Do you need to know the projectiles general equations?


Yes, but they're just SUVAT
Original post by lizard54142
Yes


Thanks so much!!!!!!!!!!!!!!!!!!!!
they have 16g but i dont know where from?
Untitled.jpg8.1KB
Original post by lizard54142
You can in fact do it without any calculations.


Show me this wonderful way lizard-senpai:mmm:
Original post by lizard54142
The 0.5m length would be vertical, but the 2.3m length would be slacked, because the distance CB is 22+0.52\sqrt{2^2 + 0.5^2}, assuming AC is 0.5m. CB < 2.3m, hence the section of the string from C to B has zero tension


Original post by Leechayy
Show me this wonderful way lizard-senpai:mmm:


See above... okay maybe a slight calculation checking if 22+0.52<2.3\sqrt{2^2 + 0.5^2} < 2.3 :wink:
Original post by lizard54142
See above... okay maybe a slight calculation checking if 22+0.52<2.3\sqrt{2^2 + 0.5^2} < 2.3 :wink:


Ohh okay, that makes sense.
So T1=50N and T2=0N

Wouldn't you find that out from redoing the process anyway? :wink:
Original post by Leechayy
Ohh okay, that makes sense.
So T1=50N and T2=0N

Wouldn't you find that out from redoing the process anyway? :wink:


It would take a while... you would find out that BAC > 90 which is impossible, so you would deduce that AC is vertical
Original post by lizard54142
It would take a while... you would find out that BAC > 90 which is impossible, so you would deduce that AC is vertical


Ohh, okay.
And with it being the very last question in the paper, its not a good position to be in to do a method like that :colonhash:
Original post by docdoc02
they have 16g but i dont know where from?


16g is the reaction of the bottom block on the 7kg block, because the three top blocks added together (4 + 5 + 7) have weight of 16g.
Original post by desmoothie
anyone know about the type of question where it says:
'What information in the question tells you _________ ?"

and the answer is usually something about a certain part being smooth/inextensible/light ect...


Original post by lizard54142
This is usually about the tension in a string being constant. The answer is "the pulley is smooth".


Yep i've been going through mark schemes today and for tension being constant it's a smooth pulley and if it asks how you know that the acceleration is the same for two objects it's usually because the string in inextensible
Original post by docdoc02
they have 16g but i dont know where from?


the reaction from the 10kg block as the three blocks on top add to 16kg
Can someone help me with 8v on this paper I don't understand the mark scheme and I don't know what the axis should be and how you know what to plot? Thanks
http://www.mei.org.uk/files/papers/m109jn_86dj.pdf
Original post by AlexParmenter
Yep i've been going through mark schemes today and for tension being constant it's a smooth pulley and if it asks how you know that the acceleration is the same for two objects it's usually because the string in inextensible


These are the questions I'll lose marks on :frown: thanks for this though

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