A block of mass 'M' is moving on rough horizontal surface with momentum 'P'. The coefficient of friction…

A block of mass 'M' is moving on rough horizontal surface with momentum 'P'. The coefficient of friction between the block and surface is ' $\mu$ '. The distance covered by block before it stops is $[\mathrm{g}=$ acceleration due to gravity $]$
  1. $\frac{2 \mu \mathrm{Mg}}{\mathrm{P}}$
  2. $\frac{\mathrm{P}}{2 \mu \mathrm{Mg}}$
  3. $\frac{\mathrm{P}^{2}}{2 \mu \mathrm{M}^{2} \mathrm{~g}}$
  4. $\frac{2 \mu \mathrm{M}^{2} \mathrm{~g}}{\mathrm{P}^{2}}$

Solution

Using kinematic relation, $v^{2}=u^{2}-2 a s$ The momentum pis given by $\begin{array}{l} p=M u \\ u=\frac{P}{M} \end{array}$ and acceleration is given as $a=\mu g$ Substituting values in Eq. (i), we get $\begin{array}{l} 0=\mathrm{u} 2-2 \mathrm{as}(\because f \in \text { alvelocity }, v=0) \\ 0=\left(\frac{\mathrm{p}}{\mathrm{M}}\right)^{2}-2 \mu \mathrm{gs} \\ \left(\frac{\mathrm{p}}{\mathrm{M}}\right)^{2}=2 \mu \mathrm{gs} \\ \Rightarrow \mathrm{s}=\frac{\mathrm{p}^{2}}{2 \mathrm{M}^{2} \mu \mathrm{g}} \end{array}$

Asked in: MHT CET 2020 (16 Oct Shift 2)

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