NEET Sample Paper NEET Sample Test Paper-68

  • question_answer
    A particle moving along x-axis has acceleration f, at time t, given by\[f={{f}_{0}}\left( 1-\frac{t}{T} \right)\], where \[{{f}_{0}}\] and T are constants. The particle at \[t=0\] has zero velocity. In the time interval between \[t=0\] and the instant when \[f=0\], the particle?s velocity  \[\,({{\nu }_{x}})\] is:

    A) \[{{f}_{0}}T\]                          

    B) \[\frac{1}{2}\,{{f}_{0}}{{T}^{2}}\]

    C) \[{{f}_{0}}{{T}^{2}}\]                       

    D) \[\frac{1}{2}{{f}_{0}}T\]

    Correct Answer: D

    Solution :

    Given the acceleration of the particle \[f={{f}_{0}}\,\left( 1-\frac{t}{T} \right)\] Or  \[f=\frac{d\nu }{dt}={{f}_{0}}\left( 1-\frac{t}{T} \right)\] \[d\nu ={{f}_{0}}\left( 1-\frac{t}{T} \right)dt\] Integrating above equation, \[\int_{0}^{V}{dv=\,\,\int_{0}^{t}{\,{{f}_{0}}\left( 1-\frac{t}{T} \right)}}\,dt\] \[\nu \,\,=\,\,\left[ {{f}_{0}}\,t-\frac{{{f}_{0}}}{T}\cdot \,\frac{{{t}^{2}}}{2} \right]_{0}^{t}\] \[\therefore \,\,\,\,\nu ={{f}_{0}}t-\frac{{{f}_{0}}}{T}\cdot \,\,\frac{{{t}^{2}}}{2}\] If \[\operatorname{f}= 0\] Then \[f={{f}_{0}}\left( 1-\frac{t}{T} \right)=0\] \[1-\frac{t}{T}=0\,\,\,\,or\,\,\,\,\,t=T\] Substituting, \[t\text{ }=\text{ }T\] in Eq. (ii), then velocity \[{{v}_{x}}={{f}_{0}}T-\frac{{{f}_{0}}}{T}\cdot \frac{{{T}^{2}}}{2}\,\,=\,\,{{f}_{0}}T-\frac{{{f}_{0}}T}{2}=\frac{1}{2}\,\,{{f}_{0}}T\]


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