1. Questions

Physics

The Golden Gate Bridge in San Francisco has a main span of length 1.28 km, one of the longest in the world. Imagine that a steel wire with this length and a cross-sectional area of 4.00 x 10-6 m^2 is laid on the bridge deck with its ends attached to the towers of the bridge, on a summer day when the temperature of the wire is 35.0°C.

(a) When winter arrives, the towers stay the same distance apart and the bridge deck keeps the same shape as its expansion joints open. When the temperature drops to −10.0°C, what is the tension in the wire? Take Young's modulus for steel to be 2.00 10^11 N/m2. (The average linear expansion coefficient for steel is 1.1 10-5°C−1.)


(b) Permanent deformation occurs if the stress in the steel exceeds its elastic limit of 3.00 x 10^8 N/m2. At what temperature would the wire reach its elastic limit?

  1. 👍
  2. 👎
  3. 👁
Anna

  1. delta L/L = (1.1*10^-5)(45)
    = 49.5 * 10^-5 meters/meter of hypothetical stretch

    that delta L/L is strain
    delta L/L = sigma/E which is stress/young's

    stress = 4.95*10^-4 * 2*10^11
    = 9.9 *10^7 N/m^2

    tension = stress * area

    =9.9*10^7 * 4*10^-6 = 396 N

    b)
    well we got 9.9*10^7 N/m^2 for a 45 degree drop
    so to get 3 * 10^8 N/m^2
    we need 45*30/9.9 = 136 degree drop
    that is 35 - 136 = -101 deg C
    (unlikely in San Francisco)

    1. 👍
    2. 👎
    Damon

Respond to this Question

First Name

Your Response

Similar Questions

  1. Math

    Los Angeles is about 385 miles from San Francisco. How far apart would the cities be on a map with a scale of 1 in. = 25 mi? If necessary, round to the nearest hundredth.

  2. Physics

    The tops of the towers of the Golden Gate Bridge, in San Francisco, are 227m above the water. Suppose a worker drops a wrench from the top of a tower. If the average force of air resistance is 22% of the force of free fall, with

  3. physics

    The tops of the towers of the golden gate bridge in san Francisco, are 227m above the water. suppose a worker drops a 655g wrench from the top of a tower. if the average force of air resistance is 2.20 percent of the force of free

  4. Math

    The bridge will span a section that is 35 meters wide, with ends of the bridge set back 2.5 m from each river bank. The engineer must apply right angle relationships because one river bank is 9 m higher than the other. What is the

  1. analytic geometry

    The main cables of a suspension bridge uniformly distribute the weight of the bridge when in the form of a parabola. The main cables of a particular bridge are attached to towers that are 600 ft apart. The cables are attached to

  2. Math

    The cable of a suspension bridge has supporting towers which are 50 ft high and 400 ft apart and is in the shape of a parabola.If the lowest point of the cable is 10 ft above the floor of the bridge, find the length of a

  3. Trig

    A bridge is built in the shape of a parabolic arch. The bridge has a span of s= 160 feet and a maximum height of h= 25 feet. Choose a suitable rectangular coordinate system and find the height of the arch at distances of 10, 30,

  4. math

    Los Angeles is about 385 miles from San Francisco. How far apart would the cities be on a map with a scale of 1 in.=100mi?

  1. English

    Not sure... Choose the citation that uses the correct MLA capitalization, punctuation, and formatting rules for a book. • Julia Alvarez. In the Time of Butterflies. San Francisco–California Press, 2005. • In the Time of

  2. math

    The main span of a suspension bridge is the roadway between the bridge's towers. The main span of the Walt Whitman Bridge in Philadelphia is 2000 feet long. This is 600 feet longer than two-fifths of the length of the main span of

  3. Grade 10 Math

    The Brooklyn Bridge in New York City is a suspension bridge that crosses the East River and connects Brooklyn to the island of Manhattan. If the origin is placed at the top of one of the cable suport towers, as shown, the shape of

  4. Grammar

    Write in the correct verb tense. 18.Joseph's English (improve, really) , isn't it? He (watch) American television programs and (study) his grammar every day since he first arrived in San Diego. Soon he will be totally fluent. I am

You can view more similar questions or ask a new question.