question_answer

    The upper end of a wire 1 m long and 2 mm radius is clamped. The lower end is twisted through an angle of\[45{}^\circ \]. The angle of shear is

A)  \[0.09{}^\circ \]                               

B)  \[0.9{}^\circ \]

C)  \[9{}^\circ \]                                     

D)  \[90{}^\circ \]

Correct Answer: A

Solution :

                In figure,\[\theta \]is the angle of twist and\[\phi \]is the angle of shear. \[B{B}=OB\times \theta =AB\times \phi \] or            \[\phi =\frac{OB\times \theta }{AB}\]                 \[=r\times \frac{\theta }{l}\]                 \[=\frac{2\times {{10}^{-3}}\times 45{}^\circ }{1}\] \[=0.09{}^\circ \]