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M1 vectors mk2

What does the question mean when it says B relative to A? what do i have to do?
Reply 1
Avatar for Notnek
Notnek
21
Original post by thefatone
What does the question mean when it says B relative to A? what do i have to do?

Please post the full question.
Reply 2
Avatar for nerak99
nerak99
13
I other words If the question says what is the velocity of a relative to b (or v.v) or what is the bearing of b relative to a (or v.v) it is very different if it says "is b a relative to a"
Original post by thefatone
What does the question mean when it says B relative to A? what do i have to do?


Get the difference between the two position vectors. It is just asking you for the distance between the two vectors. Which is the difference between the two
Reply 4
Avatar for thefatone
thefatone
OP
6
Original post by notnek
Please post the full question.


Original post by nerak99
I other words If the question says what is the velocity of a relative to b (or v.v) or what is the bearing of b relative to a (or v.v) it is very different if it says "is b a relative to a"


Original post by Funnycatvideos
Get the difference between the two position vectors. It is just asking you for the distance between the two vectors. Which is the difference between the two


At 8 am 2 ships A and B are at (i\mathbf{i}+3j\mathbf{j})km and (5i\mathbf{i}-2j\mathbf{j})respectively, from a fixed point P
Their velocities (A)(2i\mathbf{i}-j\mathbf{j}) and (B) (-i\mathbf{i}+4j\mathbf{j})

Show that t hours after 8 am the position vector of B relative to A is given by ((4-3t)i\mathbf{i} +(-5+5t)j\mathbf{j})
Reply 5
Avatar for Zacken
Zacken
22
Original post by thefatone
At 8 am 2 ships A and B are at (i\mathbf{i}+3j\mathbf{j})km and (5i\mathbf{i}-2j\mathbf{j})respectively, from a fixed point P
Their velocities (A)(2i\mathbf{i}-j\mathbf{j}) and (B) (-i\mathbf{i}+4j\mathbf{j})

Show that t hours after 8 am the position vector of B relative to A is given by ((4-3t)i\mathbf{i} +(-5+5t)j\mathbf{j})


fine the position vector of A, then of B, then subtract them and that's B relative to A.
Reply 6
Avatar for Notnek
Notnek
21
Original post by thefatone
At 8 am 2 ships A and B are at (i\mathbf{i}+3j\mathbf{j})km and (5i\mathbf{i}-2j\mathbf{j})respectively, from a fixed point P
Their velocities (A)(2i\mathbf{i}-j\mathbf{j}) and (B) (-i\mathbf{i}+4j\mathbf{j})

Show that t hours after 8 am the position vector of B relative to A is given by ((4-3t)i\mathbf{i} +(-5+5t)j\mathbf{j})

The position vector of B relative to A is the vector that goes from A to B i.e. AB→\overrightarrow{AB}.

And AB→=OB→−OA→\overrightarrow{AB} = \overrightarrow{OB} - \overrightarrow{OA}
Reply 7
Avatar for thefatone
thefatone
OP
6
Original post by Zacken
fine the position vector of A, then of B, then subtract them and that's B relative to A.


Original post by notnek
The position vector of B relative to A is the vector that goes from A to B i.e. AB→\overrightarrow{AB}.

And AB→=OB→−OA→\overrightarrow{AB} = \overrightarrow{OB} - \overrightarrow{OA}


Ah this brings back memories.. thanks all

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