Find the tension in the two wires

• kp87
In summary, the conversation discusses finding the tension in two wires supporting a 36 kg traffic light at angles of 52° and 38°. The equations used are -T1cos(52)+T2cos(38)=m*g and T1sin(52)+T2sin(38)=0. The solution is found to be T1=217N and T2=278N, but there is uncertainty about the accuracy of the trigonometry used. It is suggested to swap the sines and cosines in the equations.

Homework Statement

Find the tension in the two wires supporting the 36 kg traffic light shown in Fig. 12-57. (Assume that 1 = 52° and 2 = 38°.)

http://img15.imgspot.com/u/07/77/15/952alt.gif [Broken]

Homework Equations

-T1cos(52)+T2cos(38)=m*g
T1sin(52)+T2sin(38)=0

The Attempt at a Solution

so I found T1=-T2sin(38)/sin(52)
and plugged into the first equation and got
[sin(38)*cos(52)/sin(52)+cos(38)]*T2=353.16
and got T2 = 278N
and T1=217N

but when I put it into the webassign it is wrong...
so what am I doing wrong?

Last edited by a moderator:
It would be useful if you presented the figure somehow.

You may want to check your trig, although I can't tell for sure.

i think the sins and cosines are reversed. The vertical weight mg is opposed by the sines of the respective tensions.

denverdoc is right. Just "swap" m*g and 0.

k thanks a lot got it :)

1. What is the formula for finding the tension in two wires?

The formula for finding the tension in two wires is T = (F1 + F2)/2, where T is the tension and F1 and F2 are the forces acting on the wires.

2. How do you determine the direction of tension in the wires?

The direction of tension in the wires can be determined by considering the direction of the forces acting on the wires. Tension acts in the direction opposite to the forces, so if the forces are pulling the wires in different directions, the tension will be in the direction of the larger force.

3. What factors affect the tension in the wires?

The tension in the wires is affected by the magnitude of the forces acting on the wires, the angle of the wires, and the properties of the wires such as their elasticity and thickness.

4. How can you use a free body diagram to find the tension in the wires?

A free body diagram can be used to represent the forces acting on the wires and to determine the tension. By drawing and labeling all the forces, the tension can be calculated using the formula T = (F1 + F2)/2.

5. Can the tension in the wires ever be greater than the forces acting on them?

No, the tension in the wires can never be greater than the forces acting on them. This would violate the laws of physics and result in the wires breaking or stretching beyond their limit.