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# quick m2 question Watch

1. paper: http://www.freeexampapers.com/get_pa...M2+2004-01.pdf

mark scheme: http://www.freeexampapers.com/get_pa...2004-01+MS.pdf

can someone please explain where the I = 9i - 9j comes from for question 2b in the mark scheme? how do i do this question?

thanks

jb
2. The impulse is in the direction of i-j, so I = C(i-j) for some constant C. You're told that the magnitude of the impulse is , and so , and so [you do this bit].
3. (Original post by nuodai)
The impulse is in the direction of i-j, so I = C(i-j) for some constant C. You're told that the magnitude of the impulse is , and so , and so [you do this bit].

so its just guess work at what i and j components could be? surely there are several possibilities?
4. (Original post by jumblebumble)
so its just guess work at what i and j components could be? surely there are several possibilities?
There's no guesswork at all. A vector is defined by its direction and magnitude. It says that the impulse is in the same direction as and has magnitude , so you can work out what the vector is. Saying "it's in the same direction as " means "it's a (positive) scalar multiple of "; in other words, for some positive number . The magnitude then determines the value of , which you can find by taking the length of in terms of , and then solving for .

If it helps, write instead of . They mean the same thing.

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