JEE Main & Advanced Physics Two Dimensional Motion Question Bank Assertion and Reason

  • question_answer
                Assertion          :           When range of a projectile is maximum, its angle of projection may be 45° or 135°. Reason            :           Whether q is 45° or 135°, value of range remains the same, only the sign changes.

    A)             If both assertion and reason are true and the reason is the correct explanation of the assertion.            

    B)             If both assertion and reason are true but reason is not the correct explanation of the assertion.            

    C)             If assertion is true but reason is false.            

    D)             If the assertion and reason both are false.            

    E)             If assertion is false but reason is true.

    Correct Answer: A

    Solution :

                    Range, \[R=\frac{{{u}^{2}}\sin 2\theta }{g}\] when \[\theta ={{45}^{o}},\] \[{{R}_{\max }}=\frac{{{u}^{2}}}{g}\sin {{90}^{o}}=\frac{{{u}^{2}}}{g}\] when \[\theta ={{135}^{o}},\] \[{{R}_{\max }}=\frac{{{u}^{2}}}{g}\sin {{270}^{o}}=\frac{-{{u}^{2}}}{g}\]             Negative sign shows opposite direction.            


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