Bernoulli's Principle density and velocity

  • Thread starter physgrl
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  • #1
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Homework Statement




The density of the liquid flowing through a horizontal pipe is 1600 kg/m3. The speed of the fluid at point A is 4 m/s while at point B it is 8.0 m/s. What is the difference in pressure, PB - PA, between points B and A?



a. -1.9 x 10^3Pa

b. -3.8 x 10^4Pa

c. +4.5 x 10^4Pa

d. +5.0 x 10^4Pa

*e. -7.7 x 10^4Pa

Homework Equations



Pa+1/2*ρ*va2=Pb+1/2*ρ*vb2

The Attempt at a Solution


Pb-Pa=1/2*ρ*va2-1/2*ρ*vb2
Pb-Pa=1/2*ρ*(va2-vb2)
Pb-Pa=1/2*1600kg/m3*(4m/s2-8m/s2)
Pb-Pa=-3.84x104Pa

and the answer key says its -7.7 x 10^4Pa
what did I do wrong? :s
 

Answers and Replies

  • #2
1,198
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The answer in the book is incorrect. You have the correct answer.
 
  • #3
138
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Thanks :)
 

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