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Hey? Could someone guide me through how to do this please? 

 

 Feb 1, 2016

Best Answer 

 #1
avatar+129899 
+10

We can find the resultant by summing the vector components.....

 

For the vector pointing "south," the x component is 0 and the y component =     3sin(270)  = 3*(-1)  = -3

 

For the one with the magnitude of 7  at 150 degrees, we have

 

7cos150   =  7*-sqrt(3)/2     = - (7/2)sqrt (3)   as the x component   and

 

7sin150  = 7*(1/2)  =  7/2     as the y component

 

The sum of the x components   = -(7/2)sqrt(3)

 

And the sum of the y components  =  -3 + 7/2 =  1/2

 

The resulting magnitude is given by :

 

sqrt [ (-7sqrt(3)/2)^2  + (1/2)^2 )  = sqrt(37)  = about 6.083

 

And the direction is given by:

 

arctan  [ (1/2) / (-(7sqrt(3)/2)]  =  about -4.715° + 180  = about 175.28° ........this has to be so  because the sum of the x components are negative and the sum of the y components are positive.....thus....this must be a 2nd quadrant angle

 

So......the resultant vector  = 6.083<175.28°  = (C) seems to come closest to this

 

 

 

cool cool cool

 Feb 1, 2016
edited by CPhill  Feb 1, 2016
 #1
avatar+129899 
+10
Best Answer

We can find the resultant by summing the vector components.....

 

For the vector pointing "south," the x component is 0 and the y component =     3sin(270)  = 3*(-1)  = -3

 

For the one with the magnitude of 7  at 150 degrees, we have

 

7cos150   =  7*-sqrt(3)/2     = - (7/2)sqrt (3)   as the x component   and

 

7sin150  = 7*(1/2)  =  7/2     as the y component

 

The sum of the x components   = -(7/2)sqrt(3)

 

And the sum of the y components  =  -3 + 7/2 =  1/2

 

The resulting magnitude is given by :

 

sqrt [ (-7sqrt(3)/2)^2  + (1/2)^2 )  = sqrt(37)  = about 6.083

 

And the direction is given by:

 

arctan  [ (1/2) / (-(7sqrt(3)/2)]  =  about -4.715° + 180  = about 175.28° ........this has to be so  because the sum of the x components are negative and the sum of the y components are positive.....thus....this must be a 2nd quadrant angle

 

So......the resultant vector  = 6.083<175.28°  = (C) seems to come closest to this

 

 

 

cool cool cool

CPhill Feb 1, 2016
edited by CPhill  Feb 1, 2016

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