第1个回答 2018-03-07
3、
我们把粗段标为1，细段标为2
d1=2cm=0.02m，v1=1m/s
d2=1cm=0.01m
S1=1/4πd1^2
=1/4π×0.02^2
=0.0001π m^2
S2=1/4πd2^2
=1/4π×0.01^2
=0.000025π m^2
V2=V1
v2S2=v1S1
v2=v1S1/S2
=1×0.0001π/(0.000025π)
=4 m/s
流量：V=v1S1
=1×0.001π
=3.14×10^(-4) m^3/s
选B本回答被提问者和网友采纳
我们把粗段标为1，细段标为2
d1=2cm=0.02m，v1=1m/s
d2=1cm=0.01m
S1=1/4πd1^2
=1/4π×0.02^2
=0.0001π m^2
S2=1/4πd2^2
=1/4π×0.01^2
=0.000025π m^2
V2=V1
v2S2=v1S1
v2=v1S1/S2
=1×0.0001π/(0.000025π)
=4 m/s
流量：V=v1S1
=1×0.001π
=3.14×10^(-4) m^3/s
选B本回答被提问者和网友采纳
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