JEE Main & Advanced Physics Motion in a Straight Line / सरल रेखा में गति Question Bank Non-uniform Motion

  • question_answer
    The relation between time and distance is \[t=\alpha {{x}^{2}}+\beta x\], where \[\alpha \] and \[\beta \] are constants. The retardation is               [NCERT 1982; AIEEE 2005]

    A)             \[2\alpha {{v}^{3}}\]          

    B)             \[2\beta {{v}^{3}}\]

    C)             \[2\alpha \beta {{v}^{3}}\]  

    D)             \[2{{\beta }^{2}}{{v}^{3}}\]

    Correct Answer: A

    Solution :

                    \[\frac{dt}{dx}=2\alpha x+\beta \Rightarrow v=\frac{1}{2\alpha x+\beta }\]             \[\because \]  \[a=\frac{dv}{dt}=\frac{dv}{dx}.\frac{dx}{dt}\]             \[a=v\frac{dv}{dx}=\frac{-v.2\alpha }{{{(2\alpha x+\beta )}^{2}}}=-2\alpha .v.{{v}^{2}}=-2\alpha {{v}^{3}}\]                                      \[\therefore \]    Retardation \[=2\alpha {{v}^{3}}\]


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