Solving Force and Vector Problems: Tips and Examples

[elitespart]

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Well I just set the sum of x and y components equal to 0 and got: force 3 = -65N in x and 43.3N in y which gave me a magnitude of 78.1 N and 146.3 degrees counterclockwise from x-axis. Right? Wrong? Thanks for your help.

 

[Delphi51]

Doesn't look right. I checked the vertical part - F1 has 25 N down. F3 should have 25 N up but, according to your answer, has 78.1*cos(146.3-90) = 43N up.

 

[Hannisch]

No, I don't think it's entierly correct.. I got my doubts first when it came to your angle - if you mean from the x-axis to the right (if you understand what I mean, I don't know the terminology at the moment), F3 is in the second quadrant, and if it's from the other x-axis, so to speak, it's in the fourth and neither make much sense.

I've been thinking for a while and it's your x-component that's wrong.. It's not supposed to be -65. It's supposed to be F₂ - F_1X, right? Redo this step.

Edit: Nah, the vertical's correct. The vertical is = F3 * sinθ, not cosθ. (In reply to what Delphi51 said (; )