NateRiver wrote:
I'm in pre-algebra for maths, let's say because the English system is different to the american system. Unless, you're English I'm in year 9.
I take it you're English? If you're in year 9, you'll probably find undergraduate texts quite difficult. The only reason I say this (which is nothing against you in any way

) is that "undergraduate" both here and in the US means "degree level" (i.e. at university).
Perhaps just look at the stuff you'll do for GCSE and then A Level. Your school should have standard books they use. You could maybe look at Physics for You by Keith Johnson; that's what I used at GCSE (which was a long time ago, but they've got a new edition out).