A 225 kilograms red bumper car is moving at 3.0 meters per second It hits a stationary 180 kilograms blue bumper car. The red and blue bumper cars combine and hit a stationary green bumper car of mass 150 kilograms The red, blue, and green bumper cars all combine. What is the final velocity of the combined bumper cars?

Conserve momentum through both collisions. Initially, only the 225-kilogram red car is moving, so the total momentum is 225 × 3.0 = 675 kilogram-meters per second. After all three cars combine, their total mass is 225 + 180 + 150 = 555 kilograms, giving a final velocity of 675 ÷ 555 ≈ 1.2 meters per second. The correct choice is 1.2 meters per second.

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