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Fluid Mechanics

Drag on a Sphere

When small sp...

Question

When small sphere falls freely in stokes range through a water column, which of the following statement are correct?
1. Viscosity, surface tension and gravitational forces act on the sphere.
2. There is no turbulence possible in the wake of the falling sphere.
3. Drag coefficient, $C_{d} = R / 24$ , where R is Reynolds number.
4.Proximity of the boundary moderates the drag and lift coefficients.

1 and 2

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2 and 3

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3 and 4

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2 and 4

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Solution

The correct option is D 2 and 4
$S u r f a c e t e n s i o n d o e s n o t a c t o n f a l l i n g s p h e r e a n d d r a g c o e f f i c i e n t C_{d} = 24 / R_{e}$

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The correct option is D 2 and 4Surface tension does not act on falling sphere and drag coefficient Cd=24/Re

The correct option is D 2 and 4
$S u r f a c e t e n s i o n d o e s n o t a c t o n f a l l i n g s p h e r e a n d d r a g c o e f f i c i e n t C_{d} = 24 / R_{e}$