2. Solved Papers
  3. CMC Medical

CMC Medical CMC-Medical Ludhiana Solved Paper-2015

  • question_answer
    A uniform spring of mass 10 g having mass per unit length 0.25 g/cm is attached to spring at one end and to a fixed wall at the other end. The string has stiffness 160 \[N{{m}^{-1}}\] and stretched by 1.0 cm. If the wave pulse is produced on string near the fixed rigid support, then the time will it take to reach the spring is

    A)  0.3 s                     

    B)  0.05 s 

    C)  0.03 s                   

    D)  0.5 s

    Correct Answer: B

    Solution :

                    Given, mass per unit length (L) \[\mu =0.25\,g\text{/}cm\] \[\Rightarrow \]               \[\frac{10}{L}=0.25\] \[\Rightarrow \]               \[L=40\,cm\] Stiffness of spring, \[k=160\,N{{m}^{-1}}\] deformation, \[x=1\text{ }cm=0.01\text{ }m\] Now, force (restoring),\[T=kx=160\times 0.01\] \[=16N=16\times {{10}^{4}}\text{dyne}\] But,        \[v=\sqrt{\frac{T}{\mu }}=\sqrt{\frac{16\times {{10}^{4}}}{0.25}}\]                    \[=8\times {{10}^{2}}cm\text{/}s\] The time taken by pulse to reach the spring \[t=\frac{40}{800}=\frac{1}{20}=0.05\,s\]


You need to login to perform this action.
You will be redirected in 3 sec spinner