# Surface tension

1. May 21, 2012

### 10bunny10

1. The problem statement, all variables and given/known data
Trough a capillary with an inner radius r=1mm water flows in a form of small spherical droplets. What is the radius of the drops, the number of drops in m=10g water and the time needed the water to expire, if the surface tension of the water is =72x10^-3N/m, and the period between two drops is t=2s.

2. Relevant equations

3. The attempt at a solution
I need an idea how to imagine the situation and what to take into consideration? Help please :/

2. May 21, 2012

### 10bunny10

I tried something:
When the drop is at the end of the tube just before to fall
αl1+αl2=m0g
where m0 is the mass of one drop
2απr+2απR=m0g
R=m0g2απr/2απ
V0=4R3π/3
m0=ρV0
m0=4ρR3π/3
N=m/m0
N=3m/4ρR3π
τ=t3m/4ρR3π
t=2s

Last edited: May 21, 2012
3. May 21, 2012

### 10bunny10

Here is how I imagined it.

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4. May 21, 2012

### 10bunny10

Can anybody tell me if it is correct please?

5. May 21, 2012

### Whovian

You could've just used the edit button instead of posting 4 times on this thread that you pretty much just started.