Find the component of the Force along AC

AI Thread Summary
The problem involves breaking a 350-lb force into components along lines AB and AC, with the correct component along AC determined to be 239 lb. Initially, a calculation using cosine led to an incorrect value of 303.1 lb. The solution was clarified by redrawing the problem and applying equilibrium equations for forces in both the x and y directions. By rearranging these equations, the relationship between the components allowed for the correct calculation of AC. This approach emphasizes the importance of visualizing the problem and applying systematic methods to solve for unknowns.
Northbysouth
Messages
241
Reaction score
2

Homework Statement


The 350-lb force is to be broken into components along the
lines AB and AC.
2. The component along AC is most nearly
1. 175.0 lb
2. 186.2 lb
3. 202 lb
4. 225 lb
5. 239 lb
6. 268 lb
7. 294 lb
8. 303 lb
9. 404 lb
10. 457 lb

I have attached an image of the question


Homework Equations





The Attempt at a Solution



I had thought that I could do 350cos(30) = 303.1
But this answer is wrong. The answer is supposed to be 239 lb but I don't understand how to get it.

Help would be appreciated.
 

Attachments

  • Sample final number 2.png
    Sample final number 2.png
    40.1 KB · Views: 850
Physics news on Phys.org
Suppose instead that there was a mass producing the same force but suspended by two cables with the same geometry (but inverted, of course). How would you approach the problem of finding the tensions?
 
Now I get it. Redrawing the picture as you suggested helped me recognize that I'd dealt with this before.

ƩFy=0
0 = -350 + ACsin(60) + ABsin(50)

ƩFx=0
0= AC cos(60) - ABcos(50)

Rearranging this we get:

AB= ACcos(60)/cos(50)

Then I can plug this into the ƩFy thus allowing me to solve for Ac which is 239 lb.

Thanks for your help. That change in perspective really opened the question up.
 
Back
Top