Physics 1d03 is not a prerequisite to physics 1e03. I am not sure why it says on the website that 1d03 is a prerequisite..i know people who failed 1d03 and still took 1e03.
Anyways, i heard that physics 1d03 is kindda hard in the summer, and that Okon adjusted the marks in 1e03.
For physics, if you put in a lot of time doing capa problems, you should be good to go. Physics is about practice..the more you practice, the better you become good at it