Before I registered for Physics 121, I was thinking of taking Physics 122 instead of 121. Is that possible--enroll in 122 before 121? The requirement for my program for early addmision is either one of the Physics 121, 122, and 123.
In general, I would *strongly* advise against taking 122 before 121. The only way I can see this working would be if you already have a strong physics background (especially as pertains to vectors) and have already completed MATH125 with a good score (i.e. you are solid in both differential and integral calculus). You should note that most students who complete the whole PHYS121-3 sequence consider PHYS122 to be the most challenging of the three classes.