A bullet of mass 20 g travelling horizontally with a speed of 500 m/s passes through a wooden block of mass 10.0 kg initially at rest on a level surface. The bullet emerges with a speed of 100 m/s and the block slides 20 cm on the surface before
coming to rest. Find the friction coefficient between the block and the surface (figure 9-E13).


Mass of bullet is m = 20g = 0.02 kg


Initial velocity of bullet is v1 = 500 m/s


Mass of block is M =10 kg


Initial velocity of block is v2 = 0 m/s


Final velocity of bullet is v= 100 m/s


Let the final velocity of block when the bullet comes out of it is v’.


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Conservation of momentum





After moving a distance 0.2 it stops


By work energy principle




So, the friction coefficient between the block and the surface is 0.16.


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