9th Class Science Gravitation and Floatation Question Bank Gravitation IIT JEE Objective Problems

  • question_answer
    A body is thrown vertically upwards with an initial velocity u reaches a maximum height in 6s. The ratio of the distance travelled by the body in the first second to the seventh second is

    A)  1 : 1                      

    B)  11 : 1  

    C)  1 : 2                      

    D)  1 : 11

    Correct Answer: B

    Solution :

      From \[e{{q}^{n}}\,\,v=ugt\] At max. height \[v=0\] \[O=u-g(6)\] \[u=6g\text{ }m/s\] Distance covered in 1st second \[{{h}_{1}}=ut\frac{1}{2}g{{t}^{2}}\] \[{{h}_{1}}=6g(1)\frac{1}{2}g{{(1)}^{2}}\] similarly\[=\frac{11g}{2}\]                                            ???(1) \[{{h}_{2}}=[u(7)-\frac{1}{2}g{{(7)}^{2}}]-[4(6)-\frac{1}{2}g{{(6)}^{2}}]\] \[=u-\frac{13}{2}g=6g-\frac{13}{2}g=-\frac{g}{2}\]                            ?..(2) Now\[\frac{{{h}_{1}}}{{{h}_{2}}}=\frac{11g/2}{-g/2}=-11/1\] \[|{{h}_{1}}:{{h}_{2}}|=11:1\]


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