WEBVTT

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This is Giancoli Answers
with Mr. Dychko.

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Reynolds number is 2 times

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the average velocity of the fluid times
the radius of the tube

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times the density of the fluid
divided by the viscosity.

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So in the first case

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during the resting part of the heart cycle,

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the Reynolds number is gonna be 2 times

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35 times 10 to the minus
2 meters per second

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times 0.80 times 10 to the minus 2 meters

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converting units here into meters here

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times 1.05 times 10 to the 3 kilograms per
cubic meter for density

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and then divide that by

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the viscosity of 4 times 10 to
the minus 3 pascal seconds

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that gives about 1470 which
is less than 2000

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and so the flow is laminar through the aorta
during the resting cycle of the heart.

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Now in part (b) during exercise,

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the speed is approximately 2 times

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and so everything else is the same except
we are multiplying this by 2

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so that's the same as multiplying the entire
Reynolds number by 2

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which gives 2940

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which is more than 2000

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and so in this case during exercise,

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there's turbulent flow through the aorta.