https://www.amazon.com/Thinking-Physics-Understandable-Pract... is not free, but also excellent and gentler.
It's a little bit like The Little Schemer in that it often asks you a question and expects you to try to answer it before turning the page (or turning it upside down). The problems tend to go like "if you did this, would that (A) increase (B) decrease (C) stay the same" or "(A) increase by one (B) double (C) quadruple" -- to minimize technical machinery while still engaging you with genuine problems, not vague analogies.
The same author has a book on relativity which looked very good from the first couple of chapters I read.
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