密度ρ=1.2kg/m3的空氣,經(jīng)直徑d=1000mm的風(fēng)管流入下游二支管中如圖所示,支管1的直徑d1=500mm,支管2的直徑d2=300mm,支管的斷面流速分別為v1=6m/s,v2=4m/s,則上游干管的質(zhì)量流量為()
A.1.95kg/s B.1.75kg/s C.1.65kg/s D.1.45kg/s
A.8m/s B.4m/s C.2m/s D.1m/s
A.當(dāng)?shù)丶铀俣?img src="https://newimg.ppkao.com/2015-10/liuziyi/2015102714461030769.jpg" />u/t=0 B.遷移加速度u/s=0 C.當(dāng)?shù)丶铀俣?img src="https://newimg.ppkao.com/2015-10/liuziyi/2015102714461030769.jpg" />u/t≠0 D.遷移加速度u/s≠0