A water line enters a house 2.0m below ground. A smaller diameterpipe carries wa

Question

A water line enters a house 2.0m below ground. A smaller diameterpipe carries water to a
faucet 5.0m above ground, on the second floor. Water flows at2.0m/s in the main line and at
7.0m/s on the second floor. Take the density of water to be 1.0× 103 kg/m3. The difference
in pressure between the main line and the second floor is:
A. 7.15 × 104 Pa with the main line at the higherpressure
B. 2.65 × 104 Pa with the main line at the higherpressure
C. 7.15 × 104 Pa with the main line at the lower pressure
D. 2.65 × 104 Pa with the main line at the lower pressure
E. 9.4 × 104 Pa with the main line at the higher pressure

Explanation / Answer

bernoullis equation .       p + (1/2) v2 + gh   for main line =    p + (1/2) v2 + gh   for second floor line .     pmain   + (1/2)* 1000 * 22   + 1000 * 9.80 *0   = p2nd   + (1/2) *1000 *7.02 + 1000*9.80*7.00 . pmain   +    2000           =    p2nd  +     24500   + 68600 .     pmain -  p2nd   =   24500 + 68600 -2000 =    91100 Pa  =   9.11 x 104 Pa . that's the correct answer... which is close to E,but I think your answers are screwed up anyway. Your answers A andC are exactly the same. . Anyway...   the MAIN line is at the higher pressure,and the diff in pressure is    91100 Pa

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