Railways Technical Ability Engineering Mechanics and Strength of Materials Question Bank Strength of Materials

  • question_answer         When a weight of 100 N falls on a spring of stiffness 1 kN/m from a height of 2m, the deflection caused in the first fall is:                             

    A) Equal to 0.1 m  

    B) Between 0.1 and 0.2

    C) Equal to 0.2 m     

    D) More than 0.2 m

    Correct Answer: D

    Solution :

    \[W(h+\delta )=\frac{1}{2}k{{\delta }^{2}}\] \[100(2+\delta )=\frac{1}{2}\times 1000\times {{\delta }^{2}}\] \[=5{{\delta }^{2}}-\delta -2=0\] \[\delta =\frac{1\pm \sqrt{1+40}}{10}=0.74\,m>0.2\,m\]

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