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M1 Vectors

what does this mean?

In this question, the unit vectors i and j are horizontal vectors due east and north respectively.]
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Avatar for TenOfThem
TenOfThem
18
Original post by 50ShadesOfRay
what does this mean?

In this question, the unit vectors i and j are horizontal vectors due east and north respectively.


Just what it says, that those vectors point East and North
Reply 2
Avatar for _Katie
_Katie
5
To give an example, if something has moved by a vector of 3i + 4j, it means it has moved 3 places in the i direction and 4 places in the j direction.
Reply 3
Avatar for Tillybop
Tillybop
18
Original post by 50ShadesOfRay
what does this mean?

In this question, the unit vectors i and j are horizontal vectors due east and north respectively.]


In the question it might say (5i + 2j)kmh-1 or something like that. This means it moves 5 units in the East direction (due East means directly ----> that way) and 2 units in the North. This is because the symbol i tells you how far left/right (east/west) it is moving and how far up/down (north/south) it is moving. These vectors just tell you which direction you're going in. i is always a horizontal vector and j is always vertical. If you have -2i then it's moving west rather than east.

It think that's right anyway :smile:
Reply 4
Avatar for 50ShadesOfRay
50ShadesOfRay
OP
Original post by TenOfThem
Just what it says, that those vectors point East and North


Thankyou, how would i do this?

At time t = 0, a football player kicks a ball from the point A with position vector (2i + j) m on a horizontal football field. The motion of the ball is modelled as that of a particle moving horizontally with constant velocity (5i + 8j) m s–1.

The point B on the field has position vector (10i + 7j) m.
(c) Find the time when the ball is due north of B.
Reply 5
Avatar for 50ShadesOfRay
50ShadesOfRay
OP
Original post by Tilly-Elizabeth
In the question it might say (5i + 2j)kmh-1 or something like that. This means it moves 5 units in the East direction (due East means directly ----> that way) and 2 units in the North. This is because the symbol i tells you how far left/right (east/west) it is moving and how far up/down (north/south) it is moving. These vectors just tell you which direction you're going in. i is always a horizontal vector and j is always vertical. If you have -2i then it's moving west rather than east.

It think that's right anyway :smile:


Thank you :smile:
Reply 6
Avatar for Jarred
Jarred
18
Original post by 50ShadesOfRay
what does this mean?

In this question, the unit vectors i and j are horizontal vectors due east and north respectively.]


Essentially it's just telling you that i=(10)\textbf{i}=\begin{pmatrix} 1 \\ 0 \end{pmatrix} and that j=(01)\textbf{j}=\begin{pmatrix} 0 \\ 1 \end{pmatrix}.

A unit vector is a vector with a magnitude equal to 1. So, combining that with the fact that the vectors go due East and due North respectively, we arrive at those column vectors.

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