A block with a mass of 2.5 kg on a frictionless track collides and sticks to a stationary block with a mass of 1.75 kg and the two more together at a velocity of 3.5 m/s. What was the velocity of the first block?

A. 2.5 m/s B. 7.5 m/s C. 6.0 m/s D. 0.6 m/s E. 0 m/s

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