JCECE Engineering JCECE Engineering Solved Paper-2007

  • question_answer
    If the resultant of two forces \[2p\] and \[\sqrt{2}p\] is \[\sqrt{10}p\], then the angle between them will be

    A) \[\frac{\pi }{2}\]                                              

    B) \[\pi \]

    C) \[\frac{\pi }{3}\]                                              

    D) \[\frac{\pi }{4}\]

    Correct Answer: D

    Solution :

    Key Idea: If \[P\] and \[Q\] are two forces and \[Q\] be the angle between them, then Resultant, \[{{R}^{2}}={{P}^{2}}+{{Q}^{2}}+2PQ\cos \theta \] Using the relation                     \[{{R}^{2}}={{P}^{2}}+{{Q}^{2}}+2PQ\cos \theta \] \[\therefore \]\[{{(\sqrt{10}p)}^{2}}={{(2p)}^{2}}+{{(\sqrt{2p})}^{2}}+2(2p)(\sqrt{2p})\cos \theta \]\[\Rightarrow \]                \[\cos \theta =\frac{1}{\sqrt{2}}\Rightarrow \theta =\frac{\pi }{4}\]


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