# Homework Help: Conservation of linear momentum stationary block

1. Oct 17, 2004

### skaring

I have been trying and trying to get this problem. I am using the fact that delta K = Fd, I set 0= to Fd of one part + Fd to the other part, and it is not the correct answer.

In Figure 9-57, a stationary block explodes into two pieces L and R that slide across a frictionless floor and then into regions with friction, where they stop. Piece L, with a mass of 2.4 kg, encounters a coefficient of kinetic friction µL = 0.40 and slides to a stop in distance dL = 0.15 m. Piece R encounters a coefficient of kinetic friction µR = 0.50 and slides to a stop in distance dR = 0.34 m. What was the mass of the original block?

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2. Oct 17, 2004

### Staff: Mentor

It sounds like you are trying to apply conservation of energy. But energy is not conserved--the block exploded!

But you can use $\Delta KE = Fd$ for each piece to find the initial speeds of the two pieces just after the explosion. Do that and then use conservation of momentum to analyze the explosion itself.