Centroid education is really helpful to students in self-study competitions. When I describe this website to my classmates, it's hard not to feel that I make money by advertising. But in fact, what I said is true, and I haven't received a penny yet. Complete knowledge points, profound explanation, not sloppy. The 6.7-minute micro-class form is very conducive to the use of time. Basically, you can learn about 5 knowledge points a day without disturbing the main routine. There are some questions that are very helpful for understanding (well, the data is still a pit). It is important that every video is marked with difficulty. It is doubtful. I feel that the one selling chicken legs is top-notch, but the local shopkeeper just wants to give the best food to the public and sell it at a loss. What should this colleague think? Not to mention that they only studied the biological competition at the center of mass. The only experience is that you won't meet another person who can explain all the mathematical and physical knowledge behind biological knowledge except teaching biology. If you don't do well in the exam, you will be encouraged. If you do well in the exam, I will help you plan a good teacher in the future. The center of mass, I think, what several teachers did was a physics competition, and they surpassed it. Combine the four major mechanics and even some methods in the engineering field. Has been included in the physics competition teaching. This has greatly broadened our horizons. But the most important thing is simulation. Many simulation questions are new models and things to broaden our horizons. Live classes, summer camps, etc. Up to now, I think the center of mass has become the leader of physics training. The question focuses on one thing: Why not update the video? In my opinion, it is free in itself and there is no reason to ask for it. To make an inappropriate analogy, it's impossible to go whoring without spending money. And in my opinion, it is too low to learn physics competition only by video.