Force Problem Regarding Resultants.

[neoncrazy101]

Ok, I've been having issues with a type of homework problem and the following is the example of it. We are working with vectors and resultants.

Example of the question is f1=6m @90 degrees North. f2=8m@19 degrees South East. We have to figure out R and the degree's of R.

When I do I break the equations down into its components so I have F1x = 6cos90, f1y = 6sin90. F2x = 8cos19, F2y = 8sin19.

When I do the calculations I get F1x = 0, F1y = 6 and F2x = 7.56, F2y = 2.6. Thus then I get Rx = f1x+f2x = 7.56 and Ry = 8.6.

Thus Ex = -7.56 and Ey = -8.6.

Then I use the pythagoean theorem and I come up with E = 11.45.

Then I do tan^-1 (Ey/Ex) and I come up with 48.68 degrees.

Now then, when I put it into where I put the answer, I always get it wrong... So where did I go wrong?

 

[PhanthomJay]

Ok, I've been having issues with a type of homework problem and the following is the example of it. We are working with vectors and resultants.

Example of the question is f1=6m @90 degrees North. f2=8m@19 degrees South East. We have to figure out R and the degree's of R.

When I do I break the equations down into its components so I have F1x = 6cos90, f1y = 6sin90. F2x = 8cos19, F2y = 8sin19.

But F2y points down, it should be negative

When I do the calculations I get F1x = 0, F1y = 6 and F2x = 7.56, F2y = 2.6. Thus then I get Rx = f1x+f2x = 7.56 and Ry = 8.6.

correct your signage for F2y.

Thus Ex = -7.56 and Ey = -8.6.

Then I use the pythagoean theorem and I come up with E = 11.45.

Then I do tan^-1 (Ey/Ex) and I come up with 48.68 degrees.

Now then, when I put it into where I put the answer, I always get it wrong... So where did I go wrong?

In addition to your signage error, you are not asked to find the equilibrant, you are asked to find the resultant. They both have the same magnitudes, but their directions are opposite.