Chemical Engineering - Fluid Mechanics - Discussion

Discussion Forum : Fluid Mechanics - Section 1 (Q.No. 26)
26.
A particle A of diameter 10 microns settles in an oil of specific gravity 0.9 and viscosity 10 poise under Stoke's law. A particle B with diameter 20 microns settling in the same oil will have a settling velocity
same as that of A.
one fourth as that of A.
twice as that of A.
four times as that of A.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
22 comments Page 2 of 3.

Yadav said:   7 years ago
D is the correct option.

Manoj said:   8 years ago
No the answer is (1/4) A.
v = R2
v = (2d)2
v = 4d2.
Now, v is doubled so,
2v = 8d2.
Hence v = (1/4) d2.

Avinash Raj said:   8 years ago
Answer is D. As u is proportional to the square of D.

Sandy said:   9 years ago
Am afraid am wrong settling velocity is nothing but terminal velocity, therefore, terminal velocity is directly proportional to diameter square answer should be D if they ask about the only velocity without mentioning terminal velocity then the answer would be B that is Velocity is inversely proportional to diameter square.

Sandy said:   9 years ago
Velocity is inversely proportional to diameter.

Vb/Va= Da^2/Db^2
Vb/Va= 100/400
Vb= 1/4 Va

Vivek kumar pal said:   9 years ago
Yes, the correct answer is (d).

Aswin said:   9 years ago
I agree with @Yogi.

Yogi said:   9 years ago
v is proportional to R^2.

V2/V1 = R^2\r^2.
V2/V1 = 20^2/10^2.
V2 = 4 * V1.
So, Answer D.

Harika said:   9 years ago
This answer is wrong. It should be four times. That is option d.

G.K said:   1 decade ago
So, from this:

Vt = (g*dp^2*(raup - rauf))/(18*(viscocity)).

VA = (1/4) of VB.


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