The initial momentum is zero, so the final momentum has to be zero. Now on final momentum, yes it has to equal zero, and frankly, I am not certain what you mean by "after they hit they travel in opposite directions at 30 degree angles" UNLESS you mean one is going to the right upwards at 30 deg, and one is going LEFT down 30 deg.
IF this is so, then THe upwards momentum of one (Massblue*vblue*sin30+ plus the upward momentum of the other (massgreen*vgreen*sin-30) is zero. Now you have one other equation:
horizontal momenum:
the sum of those is zero.
You have two equations, two unknowns.
Something actually seems wrong to me with the problem, as you pointed out.
The mass of the blue puck shown below is 10.0% greater than the mass of the green one. Before colliding, the pucks approach each other with momenta of equal magnitudes and opposite directions, and the green puck has an initial speed of 8.0 m/s. Find the speeds of the pucks after the collision if half the kinetic energy of the system becomes internal energy during the collision.
The picture shows the two pucks going towards each other in a straight line (blue goes left and green goes right)and then after they hit the travel in opposite directions at 30 degree angles (blue goes down green goes up).
Why do they give an initial velocity? Shouldn't the initial momentum of the system be zero because they're going in opposite directions and equal magnitude? If this is true, then how can you solve for final velocity?
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