Why Is My Calculation of Force Along a Line Incorrect in Statics?

[vineroon]

I have been having trouble with this seemingly easy problem. You would think that it is just as simple as finding Fcos(tan^-1(3/4)), which yields the answer 320 N. However, as seen in the image, the actual answer is 420 N.

I would appreciate any help.

Thanks

 

[PhanthomJay]

You've calculated the x component of the given force. That's not what the problem is asking. You need to calculate the x and y components of the forces AB and CD, then set the sum of those x or y components equal to the x or y components, respectively, of the given force.

 

[piercas]

I understand your frustration with this problem. It is not uncommon for seemingly simple problems to have unexpected solutions. In this case, it is possible that there are other forces acting on the object in addition to the one along the line. It is important to carefully consider all the forces involved and their directions to accurately determine the net force. Additionally, it is important to use the correct formula and units when solving for force.

I would recommend double-checking your calculations and considering any other forces that may be present. If you are still having trouble, it may be helpful to seek assistance from a classmate or your instructor. Remember, in science, it is important to thoroughly analyze and consider all factors in order to arrive at the most accurate solution. Keep practicing and don't be discouraged - problem-solving is a skill that takes time and practice to develop. Best of luck!