решить При попадании y-кванта в ядро алюминия Al может образоваться ядро изотопа магния Mg. Дописать ядерную реакцию, найти дефект масс алюминия, энергию связи. = 1, 00867 а.е.м =1, 00783 а.е.м Е= 930 Мэв Al + Y = Mg + ?

1. Переменные: F — фокусное расстояние (F = 15 cм); f — расстояние между действительным изображением и взятой линзой (f = 30 см).
Расчет: d = F * f / (f - F) = 15 * 30 / (30 - 15) = 30 см.
ответ: Установленный предмет должен находиться на расстоянии 30 см от взятой линзы.
2. 1. Найдем скорость волны V = S/t = 800м/4с =200 м/с

2. найдем частоту из формулы V = l*ν

l = V/ν = 200м/с /400Гц =0,5 м
ответ: 0,5 м.
3. Изменение направления распространения света при его прохождении через границу раздела двух сред называется преломлением света.

Let's begin. One of the most common habits of children - a stooped posture (slouching). It is difficult to always keep your back straight (to keep the back upright) and not horbytsya (not to hump). I remember as a child I often say: "Sit up straight, and then thou shalt be like a question mark." I had to sit course. In life anything can happen. Some situations make us nervous and look for ways to throw out negative emotions. Sometimes children and adults find comfort in their nails and they start to bite (to bite nails). If for some reason they do not like nails, you can bite lips (to bite lips). Sprinkle ashes and honestly admit that he often bite the lips, especially when wonder. But nails ever!
If the situation is not critical, but just annoying us and requires our intervention nails and lips, we can "roll eyes» (to roll eyes). Not the most pleasant sight for your companion. Some people like to mash their fingers if they are thinking strongly about something or simply nothing to do. In everyday life this habit is called simply - crisp fingers, neck, back (to crack knuckles, neck, back). Doctors, incidentally, are not advised to do so.
Another, quite frankly, unpleasant action - is picking his nose (to pick your nose). What is in the nose, called boogers. On the nose and make another sniff, ie shmyhayut nose (she sniffs - it shmorhaye nose).
Another unpleasant sight - seeing a man who goes and splovuye saliva (to spit) Just feet. When this you see, includes feelings of disgust: Well, why like this? People can chew gum too loudly (to snap their gum), which is also annoying.
Do not cause approval and those in public talking on a cell phone (to talk on the phone). There are, of course, and urgent cases, but in most cases the cause of such phone calls - boredom. Another habit that occurs because of boredom or nerves - click ballpoint pen (to click a pen).