Вопрос школьника по предмету Физика
Решение задач по теме «Механическая работа»
Формулы, используемые на уроках «Задачи на механическую работу».
Название величины
Обозначение
Единица
измерения
Формула
Сила
F = mg
Путь
s=A/F
Macca
m= Ar/(gh)
Высота
h = Ат/ (mg)
Работа
А = Fs
Работа сил тяжести
Дж
Ат= mgh
1.Какую работу надо совершить, чтобы положить гантель весом 100 Н на
стол высотой 80 см?
Ответ учителя по предмету Физика
Ответ:
Дано: СИ
h=80 cм 0,8 м
Р=F=100Н
Найти:
А=? Дж
Решение
Работой совершается за счёт изменения энергии тела (в нашей задаче потенциальной) и находится по формуле:
A=Fh, где
F — сила, которую приложили, чтобы поднять гантель на стол, F=P=100Н;
h — высота тела над поверхностью земли (высота стола), м.
Подставим числовые значения величин и найдём чему равна работа:
А=100×0,8=80 Дж
ОТВЕТ:чтобы положить гантель весом 100 Н на стол, высота которого равна 0,8 м, нужно совершить работу равную 80 Дж.
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