Question

Can you help me solve Part a ?
https://www.dropbox.com/s/hmmlfujyj1ij0ae/Screenshot%202013-11-02%2002.50.59.jpg

Answer 1

@agent0smith

Answer 2

@bahrom7893

Answer 3

@e.mccormick

Answer 4

@Euler271

Answer 5

@Luigi0210

Answer 6

@mathslover

Answer 7

@RadEn

Answer 8

@timo86m

Answer 9

Well first you need the components of each vector, find them using sine and cosine to find horizontal and vertical components

Then.. to get the unit vector, iirc, you divide the components by the magnitude

Answer 10

This is my first time doing this :S , could you help me with the first vector please?

Answer 11

but they are 2 uknown

Answer 12

Sin45 = opposite/hypotenuse

cos45 = adjacent/hypotenuse

Answer 13

ok and then how Do I find adjacent hypo and opp ?

Answer 14

The hyp is the magnitude... given in question.

Answer 15

ok so sin(45) = y/30 ===>sin(45)30 = y ???

Answer 16

Yep. This stuff should be eeeeasy for you to learn :) you've done calculus which is much harder than this!

Answer 17

:P oh waita sec , is U=A+B+C ===> U=30+10+30 ?

Answer 18

U = (30 cos 45-10cos30) i + (10sin30 + 30 sin 45 - 30) j

Answer 19

so U is this "unit vector notation" ?

Answer 20

No i think the unit vector sum, it's a bit vague though...

Answer 21

I got it as :

A = 30 cos 45 i + 30 sin 45 j
B = -10 cos 30 i + 10 sin 30 j
C = -30 j

Answer 22

Unit vector notation is basically the same as typing a vector in it's (X, Y) form.
If a vector is (X, Y), then it's unit notation would be xi + yj.

Answer 23

hmm so its like the average vector for all 3 A B C ?

Answer 24

oh yes its not actually asking for their unit vectors. Just the components really.

Answer 25

With that, A , B and C we can easily calculate value of E further.

Answer 26

The unit vectors are i = (1, 0 ) and j = (0,1).

Answer 27

@Christos just get the components of each vector like you did above. Pay attention to when a vector is pointing in the negative x direction or negative y direction.

Answer 28

Ok thanks a lot everyone, I think I got the whole of it now . :D

Answer 29

like this is pointing in the neg x and neg y direction. You'd break it into components exact same way as the last, use the magnitude and sine and cosine.

Answer 30

ooh I see

Answer 31

I'm amazed you've done some difficult calculus, like calc 1 or 2 at least, yet are JUST learning vectors? AND you've done kirchoff's laws? And not vectors?? wtf...

Answer 32

lol easy stuff are boring , now I am studying quantum physics

Answer 33

by the way, how would I break C ??

Answer 34

well what's C's component on the x axis? hint: it's very very very small

what's C's y axis component?

Answer 35

"easy stuff are boring" haha :D

Answer 36

Is it 0 ?? ;p

Answer 37

or idk

Answer 38

yes :P

Answer 39

oh ok

Answer 40

and it's y must then be...

Answer 41

that would be 30

Answer 42

But how would I break it with such info ?

Answer 43

well the x component or i component is 0, the y or j is 30... so C = 30j, or 0i + 30j

Answer 44

I see