Re: [題目] 白努力定律的題目2
※ 引述《topractise (連月亮都幫我!)》之銘言：
: Water pressurized to (3.5 x 10^5) Pa is flowing at 5.0m/s in a horizontal pipe
: which contracts to 1/3 its former area. What are the pressure and velocity of
: the water after the contraction ?
: (A) 2.5 x 10^5 Pa , 15m/s
: (B) 3.0 x 10^5 Pa , 10m/s
: (C) 3.0 x 10^5 Pa , 15m/s
: (D) 4.5 x 10^5 Pa , 1.5m/s
: (E) 5.5 x 10^5 Pa , 1.5m/s
: 請問是A還是C呀...要怎麼算勒
體積不可壓縮：A1*v1=A2*v2
=>A*5=(1/3)A*v2
=> v2=15
Bernoullie(也許拼錯XD) equation:
P1+(1/2)*d*v1^2=P2+(1/2)*d*v2^2
3.5*10^5+0.5*1000(SI unit)*5^2=P2+(1/2)*1000*15^2
P2=2.5*10^5
so...(A)
算散射算到很煩...= =
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06/18 19:11, , 1F
06/18 19:11, 1F
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