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Spring constant question?

The bars are in equilibrium, each 2 m long,

and each weighing 73 N. The string pulling

down on the two bars is attached 0.4 m from

the fulcrum on the leftmost bar and 0.3 m

from the left end of the rightmost bar. The

spring (of constant 29 N/cm) is attached at

an angle 39 degrees at the left end of the upper bar.

If the suspended mass is 5 kg, by how much

will the spring stretch? The acceleration of

gravity is 9.8 m/s2 .

Answer in units of cm.

Diagram link: http://tinypic.com/r/18khmu/7

10 points for best answer.

1 Answer

Relevance
  • Quark
    Lv 6
    10 years ago
    Favorite Answer

    From the left to the right on figure :

    (2 * 5 * 9.8) * 1.6 + 73 * 0.6 = T1 * 0.4

    --> T1 = 501.5 N

    T2 sin 39 * 2 = T1 * 1.7 + 73 * 1

    --> T2 sin 39 * 2 = 501.5 * 1.7 + 73 * 1

    --> T2 = 735.36 N

    T2 = F_spring = k * x

    735.36 = 2900 * x

    --> x= 0.254 m

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