This showed up in the comment section from my August 2016 post in which I write a letter to my upcoming AP class. It deserves a response in a full post, because I suspect that many physics teachers are confronting just this kind of problem this time of year.
A very concerned mother here. My very strong student pulled her first C in her life in the first semester of physics. We have tutors, spoken multiple times to the teacher and everyone says that she understands the materials, and almost always does badly on the test. When asked, she says that the test is so different she does not know what to do. As an engineer who had taken high levels of physics, I am really at a lost to help her. As an experienced teacher what advice can you give her. We need to make the next upcoming semester rock! Appreciate your kind assistance.
Now, remember that I have no direct contact with this specific student, so I can't give anything more than general advice. That said, I've seen this pattern many times -- historically outstanding student who gets As in history and biology, diligent, willing to work hard with support at home from subject matter experts... yet does not perform on physics tests.
The general advice starts with recognizing that there is no magic bullet. Neither this student's parents, her tutors, her teacher, or I can instantly create success. Physics skills are learned gradually, over time. They come quicker for some than for others.
That said: It's very, very hard for me to train even good physics teachers to back off and make students struggle without giving away answers. Students (and parents!) with good intentions often treat homework as a "just get the answer" exercise without engaging in the process. Thus, in so many cases as you describe, the student's extensive support network is HURTING rather than helping. When tutors and expert parents get involved, students tend to ignore the part about "here's how to approach the problem" and think instead "thank goodness, I got the answer" -- no matter how good the tutoring might be.
So my fundamental advice is to let your daughter struggle. Give her loving emotional support, just as you would if she were on a softball team and kept striking out. When she asks questions, don't solve problems with her, don't help her figure out mistakes. It's her homework, let her do it. Instead, advise her to think all the time about the process of getting answers, the general approach to different kinds of problems, even if she doesn't get the exact right answers. Help her keep focus on the big picture of all the things she's done well -- both in and out of physics class -- and don't engage with Chicken Little talk.
It's very likely that, by year's end, she'll start making connections and improve dramatically. I've had a number of students making Cs this time of year who ended up with 4s and 5s on the AP exam. Things often click after long-term exposure to physics.
It's also possible that she pulls a C for the year. That's okay, too. I have struck out every at-bat for four games in a row; I've earned Cs on tests and in classes. Those strikeouts and Cs no more define me than they should define your daughter.