What is the combined speed of linked model train cars with different masses?

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The discussion centers on calculating the combined speed of two linked model train cars with different masses. A 230 g car moving at 0.50 m/s links with a stationary 430 g car. The correct method involves using conservation of momentum to find the speed after they connect. Participants note that an incorrect speed of 0.17 m/s may stem from unit conversion errors. Accurate calculations are essential for determining the final speed of the linked cars.
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A model-train car of mass 230 g traveling with a speed of 0.50 m/s links up with another car of mass 430 g that is initially at rest. What is the speed of the cars immediately after they have linked together?
 
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i have been working online for it but it is coming out wrong, i get .17
 
maybe you forgot your units?
 
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