A bullet of mass 20,g has an initial speed of | vedclass

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Question

(A) Given:Mass of the bullet,$m = 20\,g = 20 	imes 10^{-3}\,kg = 0.02\,kg$Initial velocity,$u = 1\,ms^{-1}$Thickness of the wall,$s = 20\,cm = 0.2\,m

Vedclass · Accepted Answer

$0.7$

Vedclass · Answer

(A) Given:Mass of the bullet,$m = 20\,g = 20 	imes 10^{-3}\,kg = 0.02\,kg$Initial velocity,$u = 1\,ms^{-1}$Thickness of the wall,$s = 20\,cm = 0.2\,m$Mean resistance force,$F = 2.5 	imes 10^{-2}\,N$According to the Work-Energy Theorem,the work done by the resistive force is equal to the change in kinetic energy:$W = \Delta K$$-F 	imes s = \frac{1}{2}m(v^2 - u^2)$Substituting the values:$-(2.5 	imes 10^{-2}) 	imes 0.2 = \frac{1}{2} 	imes (20 	imes 10^{-3}) 	imes (v^2 - 1^2)$$-0.5 	imes 10^{-2} = 10 	imes 10^{-3} 	imes (v^2 - 1)$$-0.005 = 0.01 	imes (v^2 - 1)$$-0.5 = v^2 - 1$$v^2 = 1 - 0.5 = 0.5$$v = \sqrt{0.5} \approx 0.707\,ms^{-1}$Thus,the speed is close to $0.7\,ms^{-1}$.

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