JEE Main & Advanced AIEEE Solved Paper-2002

  • question_answer
    A ball whose kinetic energy is E, is projected at an angle of \[{{45}^{o}}\] to the horizontal. The kinetic energy of the ball at the highest point of its flight will be   AIEEE  Solved  Paper-2002

    A)         E          

    B)                           \[E/\sqrt{2}\].      

    C)           \[E/2\]                  

    D)           zero

    Correct Answer: C

    Solution :

    At the highest point of its flight, vertical component of velocity is zero and only horizontal component is left. Which is as, there is no acceleration of particle in horizontal component A velocity remains constant \[{{u}_{x}}=u\cos \theta \] Given                       \[\theta ={{45}^{o}}\]              \[\therefore \]                     \[{{u}_{x}}=u\cos {{45}^{o}}=\frac{u}{\sqrt{2}}\]              Hence, at the highest point kinetic energy,              \[E'=\frac{1}{2}mu_{x}^{2}=\frac{1}{2}m{{\left( \frac{u}{\sqrt{2}} \right)}^{2}}=\frac{1}{2}m\left( \frac{{{u}^{2}}}{2} \right)\]                 \[=\frac{E}{2}\,\,\left( \because \frac{1}{2}m{{u}^{2}}=E \right)\]


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