N(кпд)=Аполезн.:Азатр.
Аполезн=Q=308000Дж
Азатраченная=mgh=423x10x15
Подставляем. Получаем. n(кпд)=308000:423x10x15
90=25 м/с
s=s1+s2=0.5s+0.5s<span>
t=t1+t2
t1=0.5s/v</span>₁<span>
t2=0.5s/v</span>₂<span>
vcp=s/t=s/(t1+t2)=s/(0.5s/v</span>₁<span>+0.5s/v</span>₂<span>) </span>Сократим на<span> s
vcp=1/(0.5/v</span>₁<span>+0.5/v</span>₂<span>)=2*v</span>₁<span>*v</span>₂<span>/(v</span>₁<span>+v</span>₂<span>)=2*25*15/(25+15)= 750/40=18.75 (</span>км/ч<span>)</span>
1)R=pl/s
R=0,4*0,8/1,6=0,32/1,6=0,2 Ом
2)I=U/R=480/600=0,8А
R=0.4 м Т=0,4 с v=? ω=?
v=2*π*R/T=ω*R
v=2*3.14*0.4/0.4=6.28 м/с
ω=v/R=6.28/0.4=15.7 рад/с
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