Vector Addition: Finding Displacement

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The discussion focuses on a homework problem involving vector addition to find displacement. The poster struggles with calculating the X and Y components of the vectors from their trip. They initially calculated the components as 69 for X and 155.3 for Y, which were deemed incorrect by another participant. The correct X component for the 294 km southwest vector is 208 km, indicating a significant error in the poster's calculations. The importance of ensuring the calculator is set to degrees and correctly accounting for the direction of each vector is emphasized.
C42711
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I am having a lot of trouble with my homework. If anyone could help me, it would be much appreciated.

The Smith's go on vacation. They travel 16.0 km north/west; then turn 27 degrees to the left and go 135 km; then 294 km south/west. What is their displacement from home?

So I found the X and Y components (using trig functions) of each vector and added them. I then tried to put those numbers into the Pythagorean theorem, but it's not working. I think my X and Y components are wrong. I got the Xs to equal 69 and the Ys to equal 155.3. This is the diagram I made: (the numbers that were given are in red, the rest I found, not sure if they are right though)
[PLAIN]http://img257.imageshack.us/img257/7742/78747381.png
By c42711 at 2011-10-30
 
Last edited by a moderator:
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Yes, something wrong with those x y components. The 294 SW vector has x component 294*cos(45) = 208 west. So your total of 69 is way too small. Got your calculator set on degrees? Note that two of the y components are north while the third one is south.
 
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