Manipal Engineering Manipal Engineering Solved Paper-2015

  • question_answer
    \[\frac{-n({{w}_{2}}-{{w}_{1}})}{Rnt}\]equals

    A) \[\frac{-n({{w}_{2}}-{{w}_{1}})}{Rt}\]

    B) \[({{\mu }_{s}}=1.4)\]

    C) \[\frac{2}{\sqrt{3}}\left( \frac{\tau }{Bi} \right)\]

    D)  None of the above

    Correct Answer: C

    Solution :

     Let\[I=\int_{{}}^{{}}{\frac{{{\sec }^{2}}x}{{{(\sec x+\tan x)}^{9/2}}}}dx\] Put sec x + tan x = t Then\[\sec x-\tan x=\frac{1}{t}\] and\[\sec x(\sec x+\tan x)dx=dt\] \[\Rightarrow \]\[\sec xdx=\frac{1}{t}dt\] Also,\[\sec x=\frac{1}{2}\left( t+\frac{1}{t} \right)\] \[\therefore \]\[I=\frac{1}{2}\int_{{}}^{{}}{\frac{\frac{1}{t}\left( t+\frac{1}{t} \right)}{{{t}^{9/2}}}}dt\] \[\Rightarrow \]\[I=\frac{1}{2}\int_{{}}^{{}}{\frac{1}{{{t}^{9/2}}}+\frac{1}{{{t}^{13/2}}}dt}\] \[\Rightarrow \]\[I=-\frac{1}{7{{t}^{7/2}}}-\frac{1}{11{{t}^{11/2}}}+K\] \[\Rightarrow \]\[I=-\frac{1}{{{t}^{11/2}}}\left\{ \frac{{{t}^{2}}}{7}+\frac{1}{11} \right\}+K\] \[\Rightarrow \]\[I=-\frac{1}{{{(\sec x+\tan x)}^{11/2}}}\] \[\left\{ \frac{1}{11}+\frac{1}{7}{{(\sec x+\tan x)}^{2}} \right\}+K\]


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