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What is the velocity of the other piece? Which was did it go?

What is the velocity of the other piece? Which was did it go?-example-1
User Rob Spoor
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1 Answer

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To solve the problem we use conservation of momentum. The momentum is given by:


p=mv

before the block exploded the momentum was zero, then we have the conservation expression:


m_1v_1+m_2v_2=0

In this case mass one is 8 kg, velocity one is 5 m/s (positive since is moving to the right) and mass two is 12 kg; plugging these values and solving for velocity one we have:


\begin{gathered} 12v_2+(8)(5)=0 \\ 12v_2=-40 \\ v_2=-(40)/(12) \\ v_2=-3.33 \end{gathered}

Therefore, the velocity of the second piece is -3.33 m/s which means that its magnitude is 3.33 m/s and it is moving to the left.