In the Stoke's experiment of falling sphere. if is found that a sphere of 5 mm diameter falls in a liquid with terminal velocity 20 mm/s giving a drag coefficient of 240. The ratio of specific gravities is 2.85. Which one of the following is the kinematic viscosity of the liquid in stokes?

3.5

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10.0

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225.0

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1000.0

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Solution

The correct option is B 10.0
$D r a g c o e f f i c i e n t, C_{D} = \frac{24}{R e}$

$∴ R e = \frac{24}{240} = 0.1 < 1.0$

$N o w R e = \frac{V D}{v}$

Given V = 20 mm/s = 2 cm/s

D = 5 mm = 0.5 cm

$∴ v = \frac{2 \times 0.5}{0.1} = 10 s t o k e s$

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In the Stoke's experiment of falling sphere. if is found that a sphere of 5 mm diameter falls in a liquid with terminal velocity 20 mm/s giving a drag coefficient of 240. The ratio of specific gravities is 2.85. Which one of the following is the kinematic viscosity of the liquid in stokes?

The correct option is B 10.0Drag coefficient, CD=24Re ∴ Re=24240=0.1<1.0 Now Re=VDv Given V = 20 mm/s = 2 cm/s D = 5 mm = 0.5 cm ∴ v=2×0.50.1=10 stokes

The correct option is B 10.0
$D r a g c o e f f i c i e n t, C_{D} = \frac{24}{R e}$

$∴ R e = \frac{24}{240} = 0.1 < 1.0$

$N o w R e = \frac{V D}{v}$

Given V = 20 mm/s = 2 cm/s

D = 5 mm = 0.5 cm

$∴ v = \frac{2 \times 0.5}{0.1} = 10 s t o k e s$