This is a free online book created through the Connexions project at Rice University and released under the Creative Commons CC-BY license.
Most concepts seem to be reasonably well motivated. E.g., the equation for torque in terms of force isn't presented until after some physical examples.
There are plenty of homework problems, but a seemingly complete lack of problems of a symbolic rather than numerical nature.
The layout is amateurish (probably due to the limitations imposed by the Connexions software, and their decision to release the book in a variety of formats), but there is a large amount of very professional looking line art done in a consistent style.