"The child is fascinated by the snack bar."
Translation:Het kind is gefascineerd door de snackbar.
The snackbar isn't doing the fascinating, if you get what I mean. The child is fascinated, meaning that fascinated is the state that it's in. In Dutch, that means "het kind is gefascineerd" is correct. The difference becomes clearer in these two sentences: "de hond wordt gevoerd": the dog is being fed, versus "de hond is gevoerd": the dog has been fed. Again, "is" denotes a state, or something that is complete and somewhat static, and "wordt" denotes a process.