# physics

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1. Air flowing through a vent pipe of cross-sectional area 21[m^2] is traveling 0.89[ms^-1].
What is the flowrate?
[18.7 m3s-1]
Answer with three significant figures (don't forget to round!) or N/A if there is not enough information to answer the question.

2. Before the vent pipe (in problem 1) ejects the air, the pipe becomes smaller in cross-sectional area. The new cross-sectional area is 17[m2]. What is the new velocity?
[ms-1]
Answer with three significant figures (don't forget to round!) or N/A if there is not enough information to answer the question.

I don't understand number 2

• physics -

1.
Flowrate=A•v=21•0.89 = 18.69 m³/s
2.
A₁v₁=A₂v₂
v₂=A₁v₁/A₂=21•0.89/17=1.1 m/s

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