General

Mechanical engineering and electrical engineering are not that similar. I've never really been that into circuits/electricity and I really enjoyed ME. Mechanical engineering is topics like solid mechanics, fluid dynamics, heat transfer, thermodynamics and courses that build off those things. A lot of the applicability into electrical circuits was pretty much only covered in our systems class, and that was never really about circuits. It definitely doesn't hurt to know, since electricity is analogous to many other systems though.

I've always enjoyed math and science. As long as you also have a passion for design, I'd say go for engineering.

Dude, doing a pure Physics degree will be MUCH harder than getting an ME degree.
ME is all easily seen and you can easily wrap your mind around the stuff you study. With Physics however, you can get into really crazy theoretical stuff.
Also, you're pretty much forced into academia is you major in Physics.

I don't know how your school is, but it would be pretty hard to double major in two COMPLETELY different sciences. Because each one needs A LOT of classes.
I double major in Chemistry and Dramatic Art, but that's because my school makes you take twice as many gen eds as most schools and I have room within my science major to compensate for a completely unrelated double major. Also, because my Dramatic Art major only requires 8 classes.

Hi neighbor.

Chemistry is a very broad field itself and only gets better the more specialized it becomes. It'll be daunting but if you stick with it, it gets very enjoyable

wow, this is some great input. Thanks guys. i guess ill try to make my decision from here, i guess a double major is almost completely out the window

If you think mechanical engineering and physics are pretty much the same, prepare to be sorely disappointed. Engineering physics/math typically stop after the basic/classic trio and don't go much deeper, since they don't have to. Mechanical engineers will probably take more physics after that, though they seem to focus more on superficial physics from what I've seen from my friend who went into that major.

Does UCSD even accept 3 on AP exams as credit?. Anyways, if you honestly like physics and can do well in the college-level physics courses, no one's stopping you from majoring in it. Major in what you enjoy, not in a major that brings good money but you won't like.

I checked the ucsd website for you. both majors mostly share the same set of 10-11 classes for the first two years, making so that you won't waste time declaring one major or the other. I would recommend starting off in the engineering major because in most universities, it is easier to switch out of engineering than to switch into an engineering major due to engineers being hosted in a different school within the university. university upper division physics is also very different from ap physics (lower division is relatively the same) and conceptually much more difficult to wrap around in your mind.

lastly, I wouldn't recommend a double major because any engineering major is already as hard as it sounds. unless you have interest in utilizing both majors together or you have a genuine interest in both and are willing to invest many extra hours, I wouldn't do it.

Just try out your first ME course. If you like it a lot then go ahead. If not then try Electrical. If that doesn't work either than stay in Physics. Double majoring in both ME and EE is going to be hard but it's convenient in a way that many same courses are required in the two fields so it's kind of hitting two birds with one stone. However it's going to be hard regardless.
As for scholarships, fastweb is a great site.

Umm ME is not like physics *10 if you are referring to physics in general and not high school "physics". Physics is more math based and requires more abstract thinking because in general if you are pursuing a PhD in physics it will be based on things that can't be measured empirically so easily and usually requires computer simulations etc.
Physics and ME are not even the same thing. If you major in ME you will take a few math classes like Calculus and DE as well as some design classes then it will be all filled with specific courses on thermodynamics,fluid dynamics, and properties of materials. Physics will cover things like optics, electromagnetic radiation, theoretical physics, QM, statistical thermodynamics etc.

Since you are going in as a freshmen you shouldn't have your major decided and change it to undeclared. Go through your first two years completing your GE and take one or two pre req courses for ME and Physics to see which you like more. A lot of people change their majors by the time they are juniors in college and preparing to take upper division courses.

I had changed my major three times. Things happens and your interest grow.