How do free-body diagrams (FBD's) help me solve problems?
Free-body diagrams are critical in newtonian mechanics, because it gives each force a voice and clarity. Looking at a worded or diagrammatic question, it is easy to get lost in aspects of the problem that are less important or entirely useless. An FBD distills the essence of the problem into its simplest form, enabling the logician in you to put that precious information to good and efficient use.
What is the difference between a chemical and a nuclear reaction?
Chemical reactions involve the movement of electrons, generally from the outer shell. Nuclear reactions engage the atomic nuclei. Since the strong force ()the strongest force in the universe) binds nuclei, the energy (on average) for a nuclear reaction is significantly larger than a chemical reaction.
Should I use the Common Application to apply to as many schools as I possibly can, so that I improve my chances?
Nope nope nope. Numerically, your chances may be higher, but you're spreading yourself dangerously thin. Remember, each college still has additional questions and essays. You don't want your top schools getting lost in the pool of fillers that you've created. Apply to about 10, and do your best on them. Anything more, and you can assure yourself that all your applications are suffering. There are obviously exceptions, but less so than you would like.