A great example of a physical boundary is a mountain. For example, the Pyrenees Mountains, which serve to separate France and Spain, are a physical boundary. So are the Ural Mountains which separate Europe and Asia. Along with mountains, oceans, seas, even deserts are examples of physical boundaries.
An average size apple weighs 6.4 ounces, which is equal to 180  grams. One apple contains approximately 91 calories and 3 grams of  dietary fiber.
Apparently the largest apple ever recorded was about 3lbs, which is about 1360g. Using that same page, that says that Americans eat on average 19.6 lbs of apples or 65 apples a year, that gives a mass of 136g per apple eaten by Americans on average. It really depends. A Mac book Pro weighs 2490 grams, while and Izod Classic only weighs 190 grams, both being Apples.