Запишем сначала КПД молота нагревания тела:
https://self-edu.ru/htm/oge2017_phis_30/files/22_25.files/image001.gif
где Q – полезная работа; E – затраченная работа. За полезную работу примем нагревание детали на ∆T=20 °С, то есть
https://self-edu.ru/htm/oge2017_phis_30/files/22_25.files/image002.gif
где https://self-edu.ru/htm/oge2017_phis_30/files/22_25.files/image003.gif - удельная теплоемкость стали; m=200 кг – масса стальной детали. Затраченная работа – это энергия, выделившаяся при n падениях молота массой M=10 000 кг. Энергия одного падения равна потенциальной энергии молота на высоте h=2,5 метра равна Mgh. Тогда при n падениях выделится энергия
https://self-edu.ru/htm/oge2017_phis_30/files/22_25.files/image004.gif
Подставляя эти величины в формулу КПД, имеем:
https://self-edu.ru/htm/oge2017_phis_30/files/22_25.files/image005.gif
откуда число ударов молота равно
https://self-edu.ru/htm/oge2017_phis_30/files/22_25.files/image006.gif
ответ: 32.
Объяснение:
По ссылкам файлы-картинки с решением
My family is not big.
I Christine. I am 11 years old and I study at a secondary school. I'm tall. I love to dance and learns.
My mother's name is Nataliya Yurievna. Her 38 years., and she works as a stylist in the store. My mother is very stylish and very strict.
My dad's name is Dmitriy. His 41 year, and he works in the office. My father was very strict and very smart. He loves to play Board games, and we often with them in their play.
My grandmother did not live together with us, but she came to me every day. And on this I come to it every weekend and holidays. We are walking a her dog and then I read my favorite book of fiction. I go to sleep about 12 hours on the weekends and during the 10 on weekdays.
It so happened that my parents got divorced, and I live alone, in a place with my mother.
I really want to live with my grandmother. We are friendly with my grandmother and very well get along.
