BCECE Engineering BCECE Engineering Solved Paper-2003

  • question_answer
    Two bodies of different masses \[{{m}_{1}}\]and \[{{m}_{2}}\]are dropped from different heights \[{{h}_{1}}\]and \[{{h}_{2}}.\]he ratio of the times taken by the two bodies to fall through these distance is:

    A) \[{{h}_{1}}:{{h}_{2}}\]                   

    B)                   \[\sqrt{{{h}_{1}}}:\sqrt{{{h}_{2}}}\]                       

    C)                   \[{{h}_{1}}^{2}:h_{2}^{2}\]                        

    D)                   \[{{h}_{2}}:{{h}_{1}}\]

    Correct Answer: B

    Solution :

    Let \[{{t}_{1}}\]and \[{{t}_{2}}\] be the times taken by the two bodies to fall through the heights hi and \[{{h}_{1}}\] and \[{{h}_{2}}\]respectively, then \[{{h}_{1}}=\frac{1}{2}gt_{1}^{2}\]and \[{{h}_{2}}=\frac{1}{2}gt_{2}^{2}\] \[\Rightarrow \]\[{{t}_{1}}=\sqrt{\frac{2{{h}_{1}}}{g}}\]and \[{{t}_{2}}=\sqrt{\frac{2{{h}_{2}}}{g}}\] \[\therefore \]  \[{{t}_{1}}:{{t}_{2}}=\sqrt{\frac{2{{h}_{1}}}{g}}:\sqrt{\frac{2{{h}_{2}}}{g}}\] \[=\sqrt{{{h}_{1}}}:\sqrt{{{h}_{2}}}\]


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