JEE Main & Advanced Sample Paper JEE Main Sample Paper-29

  • question_answer
    If \[v=Ax+B{{e}^{-ct}}\] where v is velocity, \[x\] is distance, t is time then dimensions of A, B and C are :

    A) \[L{{T}^{-1}},L,T\]            

    B) \[{{T}^{-1}},L{{T}^{-1}},{{T}^{-1}}\]

    C) \[L,L{{T}^{-1}},T\]            

    D) \[T,T,T\]

    Correct Answer: B

    Solution :

    \[2k=2a\,({{t}_{1}}+{{t}_{2}})\] \[{{t}_{1}}{{t}_{2}}=-1\] \[{{k}^{2}}={{a}^{2}}\left[ \frac{2h}{a}-2 \right]\] gives dimensionless values \[{{y}^{2}}=2a(x-2a)\]     \[a=2\] gives dimensionless values \[{{y}^{2}}=4(x-4)\]         \[\left| \begin{matrix}    2-1 & 3-4 & 4-5  \\    1 & 1 & -k  \\    k & 2 & 1  \\ \end{matrix} \right|=\,\left| \begin{matrix}    1 & -1 & -1  \\    1 & 1 & -k  \\    k & 2 & 1  \\ \end{matrix} \right|\] powers are dimensionless \[=\,\left| \begin{matrix}    1 & 0 & 0  \\    1 & 2 & 1-k  \\    k & k+2 & 1+k  \\ \end{matrix} \right|\]


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