You are missing the summary page in your collection. It would be better if you took the video above as a summary for your topic.

Also, you might have forgotten to put the references and other resources for further reading. You could have added the college physics'' eBook as a resource along with other resources like Isaac physics. 

After going through this portfolio i found is very informing and done very well, each section is broken up nicely to help take each topic one by one and understand it further. I liked the way you ranked your question at the end in difficultly order and the way it shows the solution is very helpful, however i would break the question up to each page. This way you can go through a topic and attempt the question straightaway. I would also have more videos and diagrams throughout to help visually get your point across, and help with learning. The portfolio is also missing a reference page, which would help if i wanted to read further into the topics and gain a better understanding.