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mechanics 1 question ....help me plz ..its tomorrow!! watch

1. kosy91 and kameo ...you guys free till when !!! ...could you both help or anyone else willing to help me later...cuz i have finished almost everything along with this ...the only thing that irritates me now and is left to finish is VECTORS!!! could you help me in that!! do reply!
2. (Original post by kosy91)
maybe this could better explain my method

EDIT: its -2T^2 cos....
coul you plz read my mssg on page 2 of this thread!
3. (Original post by Kameo)
Yh (90-a) It's hard to explain without diagrams.

check out this vid : http://www.youtube.com/watch?v=rC2IQ3R5im4
could you plz read my mssg on page 2 of this thread!
4. Um, yes, I timesd by 2, its even in the markscheme that you provided :P I just moved the 2 from the front to the back. No difference :P

And yes, you just resolve the two tensions, and then add them together. It's fine

And, yes, I'll help you with vectors to the best I can
5. (Original post by bluefire)
coul you plz read my mssg on page 2 of this thread!
ofcourse i can help you...as long as i havent forgotten the stuff.
you know by the time you reach m3, like me, you will forget half the stuff of m1
6. (Original post by 2710)
Um, yes, I timesd by 2, its even in the markscheme that you provided :P I just moved the 2 from the front to the back. No difference :P

And yes, you just resolve the two tensions, and then add them together. It's fine

And, yes, I'll help you with vectors to the best I can
thanks for agreeing to help me!! are you giving it tomorrow?
7. (Original post by kosy91)
ofcourse i can help you...as long as i havent forgotten the stuff.
you know by the time you reach m3, like me, you will forget half the stuff of m1
well i do understand that but it might take about an hour or a half ..hhope thts fine with you??
8. (Original post by bluefire)
thanks for agreeing to help me!! are you giving it tomorrow?
Giving what tomorrow? Do you mean the exam? Lol, I done that a year ago, got pretty good as well :P
Oh and Kosy, Im the same as you :P
9. here is the vectors question ...i don't get the c) part how and why or what to do? when giving the exam for first time a new vector question comes up i am able to do the simple postion vector of A & B , when they collide the time and its relative position vector but after that where the tricky part is .....i just don't know how to go on with it as in what to do??? i get clueless!!!

srry for making it so long but i felt as if iam ryt now in the examination hall and i am stuck where no one is there to help me but me {clueless me} !!!aggghh i will stop right here but i hope all of u understood my misery with vectors!! hope u all would change that for tomorrow!!
10. (Original post by 2710)
Giving what tomorrow? Do you mean the exam? Lol, I done that a year ago, got pretty good as well :P
Oh and Kosy, Im the same as you :P
i get it now ...ohh i thought u were going to give m1!!
11. (Original post by bluefire)
well i do understand that but it might take about an hour or a half ..hhope thts fine with you??
no problem....i am always ready to help anyone that needs it!!!
12. (Original post by bluefire)
here is the vectors question ...i don't get the c) part how and why or what to do? when giving the exam for first time a new vector question comes up i am able to do the simple postion vector of A & B , when they collide the time and its relative position vector but after that where the tricky part is .....i just don't know how to go on with it as in what to do??? i get clueless!!!

srry for making it so long but i felt as if iam ryt now in the examination hall and i am stuck where no one is there to help me but me {clueless me} !!!aggghh i will stop right here but i hope all of u understood my misery with vectors!! hope u all would change that for tomorrow!!
where's the question??!!
13. Q2
Attached Images

14. (Original post by kosy91)
no problem....i am always ready to help anyone that needs it!!!
heyy are you there?
15. (Original post by bluefire)
Q2
There is no q2. But Ill assume that you mean the stuff in Red.

So what dont you understand about it? First of all, you have to keep you head when doing these questions. When I do these questions I have the X and Y axis in my head.

At t=0, A is at 7i -10j, so I plot it in my head, 7 across and 10 down from the origin just like you would with normal coordinates. Plotted and saved. Now it says, when t=3, it changes speed. So you need to know what point it is at.

So you know that the speed of this thing is (-5i + 8j) m/s . So after 1 second, it will ave gone left 5 and up 8.

So if you imagine this in your head, and then right it down, it will be:

(7i - 10j) the original point + (-5i + 8j) x3 (for 3 seconds)

This will give you the point it is at, at 3 seconds.

And then you do the same with the rest, but you have unknowns such as U and V. You need make sure everything is clear, ie, U is the X axis component and V is the Y, in this question.
16. ok here's part c)

distance= speed x time.

when t=3, the position vector is going to be 7i - 10j + 3(-5i + 8j)= -8i + 14j.

so now... after 4s, it is at origin, therefore -8i + 14j + (ui + vj)=0

from here, equate the i and j parts and get u and v

ok??
17. as for part d)

for it to be south of A, it must have the same i position.

therefore, 7i... + 3(-5i + ...) + t(ui + ...)= 7i

from above you know that u=2, so this gives you 7.5s

thus, total time is 3 + 7.5= 10.5s
18. okk got it ...then for the next part what will we do?
19. i posted part d) above
20. (Original post by kosy91)
as for part d)

for it to be south of A, it must have the same i position.

therefore, 7i... + 3(-5i + ...) + t(ui + ...)= 7i

from above you know that u=2, so this gives you 7.5s

thus, total time is 3 + 7.5= 10.5s
what came from where ?? srry but i am really bad at such questions ...cant imagine them , also cant imagine whhat is going to happen tomorrow?!!!

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