Ответ:
Объяснение:
234/90Th--->234/91Pa+0/-1e
234/91Pa----->234/92U+0/-1e
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Кпд=(T1-T2)/T1
T1=T2/(1-кпд)=275/(1-0,45)=500 К
<span>вроде так
V1=L / T1
V2=L / T2
Vsum = (L/T1) + (L/T2) = L * (T1+T2) / (T1*T2)
Tsum = L / Vsum = (T1*T2) / (T1+T2) = 45 сек</span>