JEE Main & Advanced Physics Work, Energy, Power & Collision / कार्य, ऊर्जा और शक्ति Question Bank Self Evaluation Test - Work, Energy and Power

  • question_answer
    . A particle of mass 10 g moves along a circle of radius 6.4 cm with a constant tangential acceleration. What is the magnitude of this acceleration if the kinetic energy of the particle becomes equal to \[8\times 1{{0}^{-4}}J\]by the end of the second revolution after the beginning of the motion?

    A) \[0.1 m/{{s}^{2}}\]

    B) \[0.15 m/{{s}^{2}}\]

    C) \[0.18 m/{{s}^{2}}\]

    D) \[0.2 m/{{s}^{2}}\]

    Correct Answer: A

    Solution :

    [a] Given: Mass of particle, \[\operatorname{M}=10g=\frac{10}{1000}kg\] radius of circle \[R=6.4\text{ }cm\] Kinetic energy E of particle \[=8\times 1{{0}^{-4}}J\] acceleration \[{{a}_{t}}=?\] \[\frac{1}{2}m{{v}^{2}}=E\Rightarrow \frac{1}{2}\left( \frac{10}{1000} \right){{v}^{2}}=8\times {{10}^{-4}}\] \[\Rightarrow {{v}^{2}} = 16\times {{10}^{-2}}\Rightarrow  v=4\times {{10}^{-1}} = 0.4 m/s\] Now, using \[{{\operatorname{v}}^{2}}={{u}^{2}}+2{{a}_{t}}S~~~~~\left( s=4\pi R \right)\] \[{{\left( 0.4 \right)}^{2}}={{0}^{2}}+2{{a}_{t}}\left( 4\times \frac{22}{7}\times \frac{6.4}{100} \right)\] \[\Rightarrow {{a}_{t}}={{\left( 0.4 \right)}^{2}}\times \frac{7\times 100}{8\times 22\times 6.4}=0.1m/{{s}^{2}}\]


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