posted by Don .
a 2000kg car traveling east at 24m/sec enters an icy (frictionless) intersection and collides with a 3600kg truck traveling south at 10 m/sec. If they become coupled together in the collision, what is their velocity immediately after impact?
The final momentum is the vector sum of the two initial momenta, which are perpendicular in this case. The eastward component is 48,000 and the southward component is 36,000 kg m/s. Note that you have a 3:4:5 right triangle. Divide the resultant momentum of 60,000 kg m/s by the combined mass for the final speed.