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**1. Homework Statement**

A bullet with a mass of 7.00g is fired horizontally with a speed of 450m/s , into a wooden block with mass of 0.810kg , initially at rest on a level surface. The bullet passes through the block and emerges with its speed reduced to 140m/s . The block slides a distance of 50.0cm along the surface from its initial position.

a) What is the coefficient of friction between the block and the surface?

b) What is the kinetic energy of the block the instant after the bullet passes through it?

c) What fraction of the initial kinetic energy was "lost" ( converted to other forms of energy) in this inelastic collision?

**2. Homework Equations**

u=F/N

M1U1+M2U2=M1V1+M2V2

**3. The Attempt at a Solution**

Im not sure how to get part a) since I dont have a force to find the coefficient of friction and I dont know how to find the velocity of the block after the bullet passes though it to determine the kinetic energy of the block. Part C should be easy but seems a little confusing. is that talking about the kinetic energy loss of the bullet or the block? ... I guess it would make more sense for that to be talking about the entire system since that takes both into account.