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OCR Physics Mechanics - 20-05-2014

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Original post by KSINE
Wasn't it 21.25kg? mass of ostrich was 170, 170/8=21.25

The mass of Ostrich was 130 kg so the answer would be around 16 kg
Original post by philiath
what did everyone get for the acceleration of the spring? around 16ms^-2?


I got 6.56 ms-2
Original post by philiath
what did everyone get for the acceleration of the spring? around 16m. Yeah I did :smile:
I got 6.42 metres per second. Because there was 3N acting down, the force constant was 50, and extension was 0.1 m. So the force acting up was 5 N. So the resultant force is 2N acting up. And acceleration is 2 divide by (3/9.81 - mass)
Any one remember the weight of the cable car??
Reply 25
Avatar for ecomsins
ecomsins
i think i got 7000 something but i wasnt sureif there was 38000N of tension in both cables or 19000 each
Original post by ecomsins
i think i got 7000 something but i wasnt sureif there was 38000N of tension in both cables or 19000 each


So you mean like 6.1 times 10 to the power something?? Or was it 1.6 times 10 to the power something?
Reply 27
Avatar for ecomsins
ecomsins
I used 19000N in each cable and got the weight of the cable car to be 7000 something newton. what did anyone else get
I got 16,000N for weight of cable car. 38,000N was for each cable
Reply 29
Avatar for niki981
niki981
2
what did people get for the question where you had to work out the weight of an object being held by two cables that were 15 degrees to the horizontal. I know the tension of the cables was worked out in the previous question but I didn't know how to do it

I found I was really rushed for time but it was the same when I was doing past papers so I was expecting it. I didn't have time to properly think about how to answer questions, I just had to go for I and hope it was right. hopefully it will be ok though
Did nobody else get around 15000N for the weight of the cable car
this is wrong because acceleration is due to net force therefore should be f=5-3=2. 2/(3/9.81) = 6.5ms^-2
is it possible to get the mark if i said the dinasour thing was 1/8 the mass of the ostrich
Original post by PatrickRA
is it possible to get the mark if i said the dinasour thing was 1/8 the mass of the ostrich


Probably because it asked what happens to the mass not what is the mass? If memory serves correctly..


Original post by daniellescales
I think 42/60 for an A maybe


I hope so then I stand a chance, what makes you think this though?
Isn't it usually around 41 for an A? I'm thinking because of no jan exams lower grade boundaries but only by afew marks something like 48-50 for an A.
Original post by Ki Yung Na
Probably because it asked what happens to the mass not what is the mass? If memory serves correctly..


Im reading the paper right now.......you were asked to estimate the mass of the bird.....so only 1 mark for reducing by a factor of 8.
Original post by JackNorman
Did nobody else get around 15000N for the weight of the cable car


You would get 15800 N if the tension of 38000N you worked out before was in each side of the cable. If it was shared out as 19000 on each side then the weight would be 38000 sin12 = 7900N
Original post by KSINE
Anyone know how many marks the question on springs was? Missed it out because i didnt see it -.-


Q7 was worth 7 marks
Original post by drbarnaby
You would get 15800 N if the tension of 38000N you worked out before was in each side of the cable. If it was shared out as 19000 on each side then the weight would be 38000 sin12 = 7900N

All I remember is I calculates the vertical component of the tension in one cable and then multiplied it by two and got around 15000 and something, so was I wrong?
Posted from TSR Mobile

No u are right because the calculated tension was of one cable not two, dnt listen to peeps some are naturally dumb..
Original post by sagar448
Posted from TSR Mobile

No u are right because the calculated tension was of one cable not two, dnt listen to peeps some are naturally dumb..


Do I need to remind you of generally accepted forum etiquette.....let alone good manners? Firstly......perhaps one shouldn't call other users names? Secondly, it is good practice in life to find out who one is talking about before talking about them. Third....read my reply.....did I say which answer was correct? If you see two cables then fine.....if you see one cable....then also fine. I will not be commenting on correct or incorrect answers.....I simply popped in to let a couple of users know what marks were given for each question since lots had asked and I had the paper right in front of me. (Hint.....why would that be I wonder?).

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