Haryana PMT Haryana PMT Solved Paper-2004

  • question_answer
    The velocity of bullet is reduced from 200 m/s to 100 m/s while travelling through a wooden block of thickness of 10 cm. The retardation assuming to be uniform, will be :

    A)  \[15\times {{10}^{4}}m/{{s}^{2}}\]                                      

    B)  \[13.5\times {{10}^{4}}m/{{s}^{2}}\]

    C)  \[12\times {{10}^{4}}m/{{s}^{2}}\]                                      

    D)  none of these

    Correct Answer: A

    Solution :

                                             Here: initial velocity \[=200\text{ }m/s\] Final velocity \[\text{(}\upsilon \text{)}=100\text{ }m/s\] distance \[s=10cm=0.1\text{ }m\] Using the-relation of equation of motion                                          \[{{\upsilon }^{2}}={{u}^{2}}+2as\] \[a=\frac{{{\upsilon }^{2}}-{{u}^{2}}}{2s}=\frac{{{(100)}^{2}}-{{(200)}^{2}}}{2\times 0.1}\] \[=\frac{10000-40000}{2\times 0.1}=\frac{-300000}{2}\] \[=-150000m/{{s}^{2}}\] \[=-15\times {{10}^{4}}m/{{s}^{2}}\] \[(-)\] minus sign denotes retardation


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