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InterviewSolution
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A pendulum bob of mass `m` hangs form a massless elastic string. The potential energy (elastic + gravitational) of the system (bob + string + earth) measured relative to the position of the bob corresponding to the normal length of the string is: (where `x` = static deformation (elongation) of the string.)A. `mgx`B. `-(1)/(2)mgx`C. `2mgx`D. `-mgx` |
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Answer» Correct Answer - B Potential energy of bob `w.r.t` given refference `= -mgx` elastic potential energy of spring `= (1)/(2) kx^(2)` `= (1)/(2) (mg)/(x) xx x^(2) = (1)/(2) mgx` Hence total potential energy of the system `= -mgx + (1)/(2) mgx = - (1)/(2) mgx`. |
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