1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Calculate tension and strain of wire

  1. Oct 27, 2016 #1
    1. The problem statement, all variables and given/known data
    A load of 1150 kg is suspended as shown in the figure. The angle θ1 = 57° and the angle θ2 = 36°.

    (a) Calculate the tension in all three wires (that is, the magnitude of the tension force exerted by each of these wires):
    Tension in left wire
    Tension in right wire
    Tension in bottom wire: 11270

    (b) These wires are made of a material whose value for Young's modulus is 1.7 × 1011 N/ m2. The diameter of the wires is 1.4 mm. What is the strain (fractional stretch) in each wire?
    Strain in the left wire
    Strain in the right wire
    Strain in the bottom wire: 4.3e-2

    2. Relevant equations
    I got the strain by using this equation:
    diameter= 1.4 radius= o.7mm= 7e-4
    pi(r)^2= pi(7e-4)^2 = 1.54e-6m^2
    11270/1.54e-6= 7.318181818= 7.3e9
    7.3e9/1.7e11= 4.3e-2

    3. The attempt at a solution
    I really have no idea how to use the angles to get the tension in the left and right wire. I have used equations with tension in the bottom wire and that got me the strain in the bottom wire.
  2. jcsd
  3. Oct 27, 2016 #2


    User Avatar
    Science Advisor

    Draw a free body diagram of the point where the three wires meet. Apply the equations of static equilibrium and solve for the two unknown tensions.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted