Предмет: Физика, автор: shar21112006

Определите коэффициент полезного действия (в %) подъёмного крана при подъёме крана при подъёме им груза на высоту 50 м.Масса груза составляет 2т,коэффициент g=10 H/кг.Полная работа равна 1,25 МДж.Указать в процентах ответ.

Ответы

Автор ответа: Vasily1975

Ответ: 80%.

Объяснение:

Для подъёма груза необходимо произвести работу A, равную изменению потенциальной энергии груза E: A=ΔE=m*g*Δh, где m=2 т=2000 кг - масса груза, Δh=50 м - высота подъёма груза. Отсюда A=2000*10*50=1000000 Дж=1 МДж. КПД крана η=(A/A1)*100%, где A1=1,25 МДж - полная работа крана. Тогда η=(1/1,25)*100%=80%.

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