Posted by Mathslover Please help on Wednesday, May 8, 2013 at 1:36am.
Consider a glass with full of water of mass density ρ=1,000 kg/m3 and height h=20 cm. There's a circular hole in the bottom of the glass of radius r. The maximum pressure that pushes the water back into the hole is roughly (on the order of) p=σ/r, where σ=0.072 N/m is the water's surface tension. This extra pressure comes from the curvature of the water surface, and it tends to flatten out the surface.
Estimate the largest possible radius of the hole in μm such that water doesn't drip out of the glass.
Details and assumptions
The gravitational acceleration is g=−9.8 m/s2 and the glass is placed vertically.
Neglect any other effects that can influence the pressure from other external sources.
- Physics Help - bobpursley, Wednesday, May 8, 2013 at 2:03am
net pressure on hole=weight-pushback
when net pressure=zero, then
= .46/9.6 millimeters=46.9 micrometers.
- Physics Help - Mathslover Please help, Thursday, May 9, 2013 at 12:24am
Sir but 46/9.6 is 4.79 tell the right answer
- Physics Help - levina, Thursday, May 9, 2013 at 7:30am
1000*9.8*0.2 = 0.072/r
1960*r = 0.072
r = 3,673 x 10^(-5) m
so r = 36,73 μm
- Physics Help - levina, Thursday, May 9, 2013 at 7:33am
sorry i mean
r = 3.673 x 10^(-5) m
so r = 36.73 μm
haha still confused with . and , :)
Answer This Question
More Related Questions
- Physics - Consider a glass with full of water of mass density ρ=1,000 kg/m3...
- physics - A typical science question young people have is "Why can a glass can ...
- physics- help me please - The pressure at the bottom of a glass filled with ...
- Physics :(( help please TT - I have a length of string and I want to know the ...
- math - A glass in the form of a frustum of a cone is represented by the diagram...
- physics - A cylindrical glass of radius r=3 cm is full of salt water of height h...
- physics - A cylindrical glass is 6cm wide. When you look from above at an angle ...
- Physics please help - A cylindrical glass of water (H2O) has a radius of 3.49 cm...
- physics - A cylindrical glass of water (H2O) has a radius of 6.12 cm and a ...
- Physics - Three identical glasses are filled to the same height with water. The ...