Static Equilibrium and tension of a beam

  • Thread starter G-reg
  • Start date
  • #1
G-reg
44
0

Homework Statement


In the figure below, a uniform beam of weight 520 N and length 3.4 m is suspended horizontally. On the left it is hinged to a wall; on the right is it supported by a cable bolted to the wall at distance D above the beam. The least tension that will snap the cable is 1200 N.

What value of D corresponds to that tension?


Homework Equations


[tex]\Sigma\tau[/tex] = 3.4m(520N) + ?



The Attempt at a Solution


I'm not really sure what to put in after what I have put in already.
I know it's conservation of torque but that's about it..
 

Answers and Replies

  • #2
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
12,641
5,782
At what point on the beam does gravity act? Draw a free body diagram and put in all the forces. Then say that the sum of all the torques is zero.
 
  • #3
G-reg
44
0
I know that gravity acts on the beam at 1.7m but I'm not seeing how I'm supposed to set the sum of the torques equal to zero..but that's probably because I'm not sure what forces are acting upon the beam besides gravity and the tension from the cable.
 
  • #4
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
12,641
5,782
There is a force at the hinge that has horizontal and vertical components Fx and Fy. If you calculate torques about the hinge, they do not contribute to the net torque. However gravity and the tension must exert equal and opposite torques about the hinge if this beam is to be in equilibrium.
 

Suggested for: Static Equilibrium and tension of a beam

  • Last Post
Replies
3
Views
285
Replies
24
Views
687
  • Last Post
Replies
2
Views
621
  • Last Post
Replies
9
Views
1K
Replies
15
Views
833
  • Last Post
Replies
3
Views
380
Replies
10
Views
316
  • Last Post
Replies
9
Views
407
  • Last Post
Replies
1
Views
660
  • Last Post
Replies
3
Views
1K
Top