JEE Main & Advanced Mathematics Applications of Derivatives Question Bank Application in Mechanics and Rate Measurer

  • question_answer
    The velocity of a particle at time t is given by the relation \[v=6t-\frac{{{t}^{2}}}{6}\]. The distance traveled in 3 seconds is, if \[s=0\]at \[t=0\]

    A)            \[\frac{39}{2}\]

    B)            \[\frac{57}{2}\]

    C)            \[\frac{51}{2}\]

    D)            \[\frac{33}{2}\]

    Correct Answer: C

    Solution :

               \[\frac{ds}{dt}=6t-\frac{{{t}^{2}}}{6}\]            Now on integrating both sides \[s=3{{t}^{2}}-\frac{{{t}^{2}}}{18}+\]constant , (where s is distance)            Now put \[t=0\], then \[s=0\] gives constant equal to 0 and putting \[t=3\], we get            \[s=3{{(3)}^{2}}-\frac{{{3}^{3}}}{18}=27-\frac{27}{18}=\frac{51}{2}\].            Aliter : \[\int_{0}^{s}{ds}=\int_{0}^{3}{\left( 6t-\frac{{{t}^{2}}}{6} \right)\,dt}=\frac{51}{2}\].


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