Work Power And Energy

A bullet of mass \(0.1 \mathrm{~kg}\) moving horizontally with speed \(400 \mathrm{~ms}^{-1}\) hits a wooden block of mass \(3.9 \mathrm{~kg}\) kept on a horizontal rough surface. The bullet gets embedded into the block and moves \(20 \mathrm{~m}\) before coming to rest. The coefficient of friction between the block and the surface is __________.

(Given \(g=10 \mathrm{~m} / \mathrm{s}^{2}\) )