Final answer:
Without specific details about dots C and D in the provided information, it is not possible to determine their motions or compare them accurately.
Step-by-step explanation:
We can determine the motions of dots C and D by looking at the information provided. From the descriptions, there seems to be no information directly relating to dots C and D. Therefore, it is impossible to ascertain if either of them is speeding up, slowing down, or moving at a constant velocity without additional context or data.