JEE Main & Advanced Physics Motion in a Straight Line / सरल रेखा में गति Question Bank Critical Thinking Questions

  • question_answer
    The acceleration of a particle is increasing linearly with time \[t\] as \[bt\]. The particle starts from the origin with an initial velocity \[{{v}_{0}}\] The distance travelled by the particle in time \[t\] will be [CBSE PMT 1995]

    A) \[{{v}_{0}}t+\frac{1}{3}b{{t}^{2}}\]     

    B) \[{{v}_{0}}t+\frac{1}{3}b{{t}^{3}}\]

    C) \[{{v}_{0}}t+\frac{1}{6}b{{t}^{3}}\]

    D)     \[{{v}_{0}}t+\frac{1}{2}b{{t}^{2}}\]

    Correct Answer: C

    Solution :

        \[\frac{dv}{dt}=bt\Rightarrow dv=bt\ dt\Rightarrow v=\frac{b{{t}^{2}}}{2}+{{K}_{1}}\] At \[t=0,\ v={{v}_{0}}\Rightarrow {{K}_{1}}={{v}_{0}}\] We get \[v=\frac{1}{2}b{{t}^{2}}+{{v}_{0}}\] Again \[\frac{dx}{dt}=\frac{1}{2}b{{t}^{2}}+{{v}_{0}}\Rightarrowx=\frac{1}{2}\frac{b{{t}^{2}}}{3}+{{v}_{0}}t+{{K}_{2}}\] At \[t=0,\ x=0\Rightarrow {{K}_{2}}=0\] \[\therefore \]\[x=\frac{1}{6}b{{t}^{3}}+{{v}_{0}}t\]


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