BCECE Engineering BCECE Engineering Solved Paper-2007

  • question_answer
    The elastic energy stored in a wire of Youngs modulus Y is

    A)  \[\frac{\text{1}}{\text{2}}\text{Y}\,\text{ }\!\!\times\!\!\text{ }\,\text{stress}\,\text{ }\!\!\times\!\!\text{  strain}\,\text{ }\!\!\times\!\!\text{ }\,\text{volume}\]

    B)  \[\frac{{{\text{(stress)}}^{\text{2}}}\text{ }\!\!\times\!\!\text{ }\,\text{volume}}{\text{2Y}}\]

    C)  \[stress\times strain\times volume\]

    D)  \[Y\times \frac{{{(stress)}^{2}}}{volume}\]

    Correct Answer: B

    Solution :

    When a wire is stretched work is done against the interatomic forces. This work is stored in the wire in the form of elastic potential energy. \[W=\frac{1}{2}\times \]stress \[\times \] strain \[\times \] volume of wire Also when strain is small, ratio of longitudinal stress to corresponding longitudinal strain is called Youngs Modulus of material of body.                                 \[\text{Y = }\frac{\text{longitudinal}\,\text{stress}}{\text{longitudinal}\,\text{strain}}\]                 \[\therefore \]  \[\text{W = }\frac{\text{1}}{\text{2}}\text{  }\!\!\times\!\!\text{  stress  }\!\!\times\!\!\text{  }\frac{\text{stress}}{\text{Y}}\text{  }\!\!\times\!\!\text{  volume}\]                 \[\text{=}\frac{{{(stress)}^{2}}\times volume}{2Y}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner