A) 1800 N
B) 2000 N
C) 2200 N
D) 2850 N
Correct Answer: A
Solution :
Key Idea: The bullet comes to rest inside the block, hence final velocity is zero. Let m be mass of bullet, travelling with initial velocity of 120 m/s (u). It comes to rest after travelling a distance of (0.12 m = 5) inside the block. Since, it comes to rest the final velocity (y) is zero. From equation of motion, we have \[{{v}^{2}}={{u}^{2}}+2\,as\] Here, \[v=0,\,u=120\,m/s,\,s=0.12\,m\] \[\Rightarrow \] \[a=-\frac{{{u}^{2}}}{2\,s}=\frac{{{(120)}^{2}}}{2\times 0.12}\] \[\Rightarrow \] \[a=-60,000\,\,m/{{s}^{2}}\] Resistive force \[F=ma\] \[\Rightarrow \] \[F=0.003\times 60,000\] F = 1800 NYou need to login to perform this action.
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