velocity after explosion?

Question

an object of mass m is moving with speed v0 to the right on a horizontal frictionless surface. it explodes into two peices.

one piece with mass (20/23)m moves to the left at velocity v0/5. second piece with mass (3/23)m moves to the right at what velocity?

Answer 1

First conservation of momentum. Mass is moving at a constant velocity to the right. It will continue at that velocity until acted on by another force, in this case, an explosion. You need to figure out the force of the explosion. SInce you know that one piece, 20/23, not only stopped moving right, it actually changed direction to be moving left at the given velocity. You need to calculate the change in velocity (kinetic energy) of the other piece, 3/23. Since this smaller piece was already travelling right at V0, it will increase in speed by the amount of kinetic energy it got from the explosion (assuming that the explosion did not blow this piece straight up). From the question, I think you are safe to assume that the small piece is travelling to the right in a straight line. good luck