It depends on your background.

For really starters, I'd suggest Paul Hewitt's book Conceptual Physics.

For A to B high school students, I'd say Resnick and Halliday's book is great.

For A+ high school students, I'd recommend Feynman's Lectures. These lectures serve as complement for the other books, but personally it's not for beginners

Cheers. 

What's the first physics textbook for undergraduate self-learner？
I'm building an app, on which I want to capture when a user enables or disables mobile data usage on his device.

I read about using android.net.conn.CONNECTIVITY_CHANGE to monitor such changes, but then I came across various posts and questions here that said that this wouldn't work, and the majority of the answers suggested to use reflection. 

These led me to believe that there is no specific event being fired when the user changes the state of mobile data that I can use.

Is it possible that a custom event can be created to handle it? If not, what would you suggest the best practice is for monitoring the state of mobile data? 

Thanks in advance
