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# M1 position vector need help! watch

1. hi for part c , I don't get how it's worked out. The mark scheme states that the method is 1/15 (-15i+12j)*t. I don't get why 1/15 is used, is it to work out how far away they are every minute? Also, why can't you just do (-15i+12j)t and go from there ? Thanks.
2. I think they mean find the displacement of A relative to B with can be found by doing . Then take the modulus of this vector and set it equal to 23 hence then get and thus so 18 minutes.
3. (Original post by Cryptokyo)
I think they mean find the displacement of A relative to B with can be found by doing . Then take the modulus of this vector and set it equal to 23 hence then get and thus so 18 minutes.
Thanks.

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