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Railways NTPC (Technical Ability) Automobile Engineering Question Bank Automobile Engineering

  • question_answer
    A hole is to be punched in a 15 mm thick plate having an ultimate shear strength of  3 N-\[m{{m}^{-2}}.\]If the allowable crushing stress in the punch is \[6\,N\]-\[m{{m}^{-2}},\] the diameter of the smallest hole which can be punched is equal to:

    A) 15 mm             

    B) 30 mm

    C) 60 mm             

    D) 120 mm

    Correct Answer: B

    Solution :

    \[\pi dt\pi =\frac{\pi }{4}\,{{d}^{2}}{{\sigma }_{c}}\] \[d=\frac{4t\pi }{{{\sigma }_{c}}}=\frac{4\times 15\times 3}{6}=30\,mm\]


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