At what speed does the dish move? (momentum: inelastic collision)

Question

In a restaurant, one cook slides a 245-g delicious pizza down the counter from left to right at 1.63 m/s. At nearly the exact same time, another cook launches a 349-g cheeseburger along the same counter from right to left at 2.21 m/s. The two items collide head‑on at the given speeds – the counter is friction‑free due to accumulated grease – and combine into a single, wonderful concoction. At what speed does the dish move?

Answer 1

Classic momentum problem taking left to right positive and right to left negative, once they collide they are attached to each other, so applying conservation of momentum: [ .245kg x 1.63m/s] - [.349 kg x 2.21m/s] =

[.245 kg + .349 kg] Vf. Solve for Vf.