Physics question about Adding 3 VECTORS?

Question

okay, so i basically know nothing about vectors, so keep it simple please.

i have a line going south west, then one going up northeast (forming an obtuse angle) and then one going straight across right. how do i find \drawthe resultant of these?

do i make the last one going the opposite direction, so the resultant can be drawn in making a 4 sided figure, or do i just draw the line across, making it resemble an 8 (not exacly, but its not an enclosed figure)

Answer 1

An arrow is used to represent a vector,which has both magnitude and direction(length=magnitude;orientation of the arrow=direction).



In vector addition, the order does not matter because vectors are both commutative and associative.The order is up to you as long as the vectors to be added are arranged properly(the tail of the second vector is on the tip of the first vector;then the tip of the second vector on the tail of the third vector and so on).

Make an arrow to represent the resultant vector.Its tail on the tail of the first vector(the one going SW) and the tip is on the tip of the last vector(the one going right or E).

That's the rule for the tip-to-tail method in adding vectors.



So as according to you "just draw a line across, making it resemble an 8".Don't make any deviations in the problem like changing the direction of a vector.Just follow the problem and do the tip-to-tail method to find the resultant vector.

Answer 2

OK you've done the hard part...finding all the x's and y's. And you've added them to get X = 212.1 and Y = 322.3. Here's how you get the direction. Recognize that X and Y are just two side of a right triangle. We usally graph the X in the horizontal direction and the Y in the vertical. And you have the hypo S = 385.8 running from X to Y. And we have... Y |\ | .\ | .. \ S |.... \ ___oX What's that gap between S and X at o? It's an angle, and that's the direction of S relative to the X axis. Let's call that gap theta = arctan(Y/X) = arctan(322.3/212.1). And there you have it, do the math and you'll have an angle theta to go along with S = 385.8. As you failed to give the basis for your angles (e.g., what's zero degrees?), I have no clue what direction those angles you gave are pointing. But using arctan(Y/X) is the way you find the direction, once you have established the zero point.

Answer 3

south west resolve to south and west



north east resolve to north and east.



third towards east.



now you have four vectors towards south north east and west. east and west opposite. so subtract and you have one vector.



south and north too opposite. so subtract. you have another vector.



now you have two perpendicular vectors. use parallelogram law of vector addition.



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