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6 Cards in this Set
- Front
- Back
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Bernoulli description
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work done on a unit volume of fluid = sum of changes in potential & kinetic energies per unit volume that occurs during flow
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Given a tapering pipe, is the pressure greater at the larger or smaller end?
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greater area, greater pressure, so pressure greater at larger end
If A₂ < A₁, then v₂ > v₁ and p₂ < p₁ |
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The pressure drop in fluid from moving from the greater end to the smaller end of a tapered pipe causes the fluid speed to
decrease, increase, or same |
increase
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If the narrowed end of the tapered pipe is raised above the larger intake end, is the pressure drop
smaller, equal, larger compared to if the pipe were horizontal? |
Larger
The potential energy term on the narrow side is larger than the PE term on the greater side. Solving Bernoulli's for p₂=p_narrow means that PE₂ is subtracted to reach p₂, so p₂ is smaller (larger pressure drop) than would have been the case otherwise. |
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Wind blows over a house with an open window & open chimney. How does air flow through?
In chimney & out window no flow in window & out chimney |
in window & out chimney
the wind lowers the pressure at the roof level, drawing air through the window & out the chimney |
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Water flows through a 4.0-cm-diameter horizontal pipe at a speed of 1.3 m/s. The pipe then narrows down to a diameter of 2.0 cm.
Ignoring viscosity, what is the pressure difference between the wide & narrow sections? |
First, find V₂ = A₁V₁ / A₂
no need to convert area units since they cancel πs cancel 2 cm² * 1.3 / 1 cm² = 5.2 m/s p₁-p₂ = ∆p = 1/2 ρ (V₂² - V₁²) = 1/2 * 1000 kg/m³ * ((5.2 m/s)² - (1.3 m/s)²) =12 675 N/m² = Pa rounding, 12700 Pa |
