Why doent the water surface collapse as the net intermolecular force acts downwards when kept in a container?
349930
it's because of elasticity(bulk modulus).The force on the surface will try to reduce the volume and but as the volume changes, there is a net upward force and an eqilibrium will be reached when outward (volume)elastic force equals the downward cohesive force. But the decrease in volume and hence the level of warer is so small(in the order of micrometre) that we don't notice it.
811736
If the water is full of air bubbles, its density is reduced. You loose buoyancy and sink.\n\nWhen there is a natural gas blow out under floating oil platforms, they have been known to go down almost instantly.
250157
This is due to hydrogen bonds forming between the water molecules, which line up molecules less efficiently (in terms of volume) when water is frozen.
974729
Gravity. Water doesn't seek its own level on the Space Station, it forms a ball-shaped blob.
65763
Because a ship has surface area, a needle doesn't. Water can flow around it, so it sinks.
875577
The bonds between particles in a liquid are pretty weak, so I think its because the energy lost in the liquid by the wave has two components; one parallel to the direction of propagation, one perpendicular to it. The energy is passed from one particle to the next, but at each interaction, energy is lost (as heat, i guess), and so the further away the observer is from the wave, the less energetic the particles are; the wave "fades". Liquid is viscose, and so the bonds between particles have a certain degree of stretch to them. Energy is lost in the transferral of momentum through these bonds. \n\nTransverse waves in air can be produced with radio frequency electromagnetic waves (but they can travel through vacuum too), or a mechanical wave could probably be created using some sort of oscillator; bonds between gas molecules are pretty much non existent, so it'd be hard :-)\n\nBulk movment of particles, like in sound waves, are much easier - just pushing the particles forward repeatedly at the right frequency is audible.
443139
BOUYANCY & SURFACE TENSION
350047
The first two factors that came to mind when I read this question have already been mentioned (surface tension and viscosity).  However,  I would describe the effect a bit differently.\n\nSurface tension provides the major cause of a liquid dribbling down the side rather than pouring cleanly from a container.  Surface tension is created by a weak bond between the molecules in the liquid and causes the molecules to form a continuous mass of particles.  Imagine water being slowly poured from a near-full glass into a small-mouthed container.  As the glass is tilted, the water slowly rolls over the lip of the glass and tends to roll down the side of the glass.  This is because the surface tension of the water is acting to keep a continous body of water and the slight angle of the glass reduces the effective force of gravity pulling the water away from the surface of the glass.  The forces pulling the liquid away from the glass are not strong enough to overcome the surface tension of the water.  The water adheres to itself, and to the glass, and streams down the side.  \n\nAs the glass is tilted further, the speed of the water exiting the glass increases and effect of gravity is increased due to greater angle of the glass with respect to the ground.  The greater forces pulling the water from the glass cause the surface tension in the water to begin to fail, and some of the water pours away from the glass, while some of the water continues to run down the side.  \n\nWhen the glass is fully inverted, the water exits the glass at maximum speed and the full effect of gravity pulls the water away from the glass.  The surface tension of the water is overcome and the water exits cleanly from the glass.  \n\nThe only effect that viscosity has on this is that high viscosity liquids pour much more slowly and the momentum effect is greatly reduced.  Thus, a greater angle is often needed to increase the gravitational effect and overcome the surface tension.
243894
Hydrogen bonding causes water to expand upon freezing.  The H-bonds cause the molecules to align into a structure that occupies more space than the liquid.  \n\nLiquid H2O does not do this because the kinetic energy of the water molecules constantly breaks any H-bonds that form.  As the kinetic energy (temperature) of the water decreases, the water becomes more dense, down to about 4 deg. C.  \n\nBelow 4 deg. C, the H-bond alignment of molecules outweighs the kinetic energy and the density of water begins decreasing.\n\nFrom Wikipedia:\nA simple but environmentally important and unique property of water is that its common solid form, ice, floats on the liquid. This solid phase is less dense than liquid water, due to the geometry of the strong hydrogen bonds which are formed only at lower temperatures. For almost all other substances and for all other 11 uncommon phases of water ice except ice-XI, the solid form is more dense than the liquid form. Fresh water is most dense at 4°C, and will sink by convection as it cools to that temperature, and if it becomes colder it will rise instead. This reversal will cause deep water to remain warmer than shallower freezing water, so that ice in a body of water will form first at the surface and progress downward, while the majority of the water underneath will hold a constant 4°C. This effectively insulates a lake floor from the cold.
383803
hey! the force acting on these spheres is the buoyant force.  buoyant force is equal to the weight of the liquid displaced by the immersed object.As in this case the weight of both spheres is the same [m*g i.e(1kg*9.8m/s2)] the buoyant force will also be the same.hence none of them "appears to lose" and both appear same.get that??!
74872
I'm sure this isn't the only material with this property.  \nDo you know what a phase diagram is?  If the line between the liquid and solid phases has a negative slope (goes down as you read it across) like the second phase diagram at this website: http://wine1.sb.fsu.edu/chm1045/notes/Forces/Phase/Forces06.htm\nAny material with a phase diagram that has the line between the liquid and solid phases as a negative slope becomes less dense (expands) when it freezes.  \nThe reason that water expands when it freezes is because when water crystallizes into ice, the structure leaves this pocket of emptyness in the middle of a ring of water molecules.  This makes the ice larger than the water it was when it was liquid.  Anything else that does this will also expand.
487982
I'd say physics rather than chemistry.  When you squeeze a bottle full of water containing a gas-filled "diver", the water is not compressed.  Only the gas in the diver compresses causing the diver to displace less water.  The cartesian diver is carefully made to be just barely buoyant, so when compressed its reduced displacement causes it to sink.
564133
all the molecules in fluid(liquid or gaseous) are always in random motion, therefore they keep striking the walls of the container , this force causes pressure on the walls of the container
104409
This is a classic problem from hydrodynamics textbooks. The short answer is, it is approximately simple harmonic motion. You can compute the restoring force caused by the displacement of the liquid if you depress a floating boat (Archimedes principle) and that then, balanced with the weight of the boat, creates the conditions for simple harmonic motion. You can approximate the period and amplitude of motion etc. \n\nHowever it gets more complicated than this of course:\n\na. There are damping forces caused by the motion of the boat through the water and the air\n\nb. The water is not completely incompressible, and the density of the water varies some with depth (a tiny effect)\n\nc. There are surface tension effects and entrainment effects\n\nd. The motion of the boat will be more complicated than simple linear motion in one dimension\n\ne. There will probably be deformation effects on the boat, changing its shape\n\nf. gravity is not constant as the boat is moving up and down a small distance in a gravity gradient\n\nand so on. \n\nHowever, the REASON that sines and cosines are so prevalent everywhere in physics is because simple harmonic motion is such a good approximation for so many things. \n\nWhy is this?\n\nWell consider Newton's Second law: F=ma, where F is force, m is mass and a is acceleration. Newton's second law is not always true, in the quantum world and in relativistic situations, but it is true under many conditions, so it is a good place to start. \n\nIn general, the force F will be some sort of nonlinear function of position x:\n\nF=F(x)\n\nHowever, if x is small, then we can approximate F(x) by a McLaurin series:\n\nF ~ F(0) + x F'(0) + h.o.t. \n\n(h.o.t. is a common acronym for higher order terms).\n\nThis then produces the equation for simple harmonic motion, when substituted into Newton's 2nd law:\n\nF(0) + xF'(0) = m d/dt(d/dt(x))\n\nMany other equations in physics like Schrodinger's equation, or wave equations with forcing, or the heat equation, or the inhomogeneous Laplace's equation include 2nd order derivatives, and can similarly be put in some form where simple harmonic motion is the result. So as strange as it seems when you are just learning about SHM in physics, it really is everywhere in all kinds of unexpected places! \n\n\nOne of my favorites is the waves of heat and cold that are travelling down into the earth from the seasonal forcing produced at the surface. Drilling down, one can observe these waves of hot and cold (with some diffusion) going back many years.
421576
Here's an interesting article that explains a little about how surface tension works in droplets.\n\n\n"Surface Tension in Water Droplets \nIntermolecular forces create the surface tension that causes these water droplets on leaves to bead up and form the smallest surface possible. The water molecules at the surface are pulled in by the cohesive force between themselves and molecules inside the droplet. The water keeps its droplet shape because there are no water molecules outside the surface to balance this inward pull. "\n\nhttp://encarta.msn.com/media_461560536_761563983_-1_1/Surface_Tension_in_Water_Droplets.html\n\nHere's another resource,\nhttp://en.wikipedia.org/wiki/Surface_tension
1047674
Intermolecular forces (vander waals, hydrogen bonds), are very much weaker than covalent or ionic bonds\nyou see, when we evaporate water in its boiling points(or other liquid), we break the intermolecular forces (in water's case, hydrogen bonds), but the heat still cannot break up covalent H-O bonds, so the chemical formula of water vapour is still H2O but with no intermolecular forces
462517
If there are bubbles of air then you will have less liquid than you are intending to have. Assuming you are calculating density via measurementof mass then the mass you get will be less than it should be for that volume of that liquid. As a result the calculated density will work out lower than it should do.