11 physics: "small drops of water assumes spherical shape due to surface tension".why do farmers plough the fields before summer?
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The cohesive forces between liquid molecules is responsible for the surface tension. The molecules of water on the surface don't have like molecules around it.So the molecules lying in the surface are attracted or pulled downward by the adjacent water molecules. So the water droplets tend to be pulled into shape of spherical due to cohesive forces.If other forces including gravity is missing,then droplets of all the fluids have spheical shape.So this spherical forms are easier to form, required less surface tension,less wall tension.More the surface tension more will be the spherical form.6.6k Views · View Upvoters · Answer requested by Sharath RajRelated QuestionsMore Answers BelowWhen a water drop falls, does it form a circular shape?Why are rain drop spherical?Why do water drops fall in that shape?Why is the shape of a water drop circular?Why does water form a ball in zero gravity and not another shape?Ask New QuestionGabe Giraldo, Masters in Mechanical EngineeringAnswered Sep 18 2015 · Upvoted by Jerzy Michał Pawlak, PhD in High Energy Physics (experimental)Oh boy! The first question I've seen that I feel confident enough to answer!
We observe the water behaving 2 different ways when placed on a surface, but why? The reason is the surface tension caused by the cohesion of the water molecules.
The two questions we need to answer are:
1. How does surface tension cause a droplet to take the shape that it does?
and
2. Why beyond a "critical point" (such as the cup of water in your example) will it no longer simply form a large droplet shape?
Lets first imagine an ideal sphere of water floating in space. The sphere forms in nature since it is the shape that requires the minimum amount of surface tension to maintain.
Fig 1. Sphere of water.
The sphere has an internal pressure pointing in all directions outward from its center and it also has a surface tension which keeps the water molecules bound in the spherical arrangement.
If we were to cut the droplet such that we have equal left and right halves, we can use Laplace's equation on the circular cross-section to figure out that:
SurfaceTension=InternalPressure∗Radius/2SurfaceTension=InternalPressure∗Radius/2
English Translation: This tells us the minimum surface tension required to support the spherical shape.
Fig 2. Circular cross section of the sphere.
Now lets consider a droplet on a surface. Observation tells us that this is no longer a perfect sphere but a kind of "squashed" sphere which has a wider base along the contact surface.
Fig 3. Droplet on a surface. Note the rounder top vs. the flatter bottom.
Lets divide out droplet now into 2 halves again, left and right halves. This gives us an deformed circular cross section to work with (due to the aforementioned squashing). Now lets divide our new cross-section into top and bottom halves.
Recall that we said the internal pressure points in all directions from the center. This tells us that the pressure in the top half is the same as the pressure in the bottom half. The key difference is that the surface curvature of the bottom half is less than that of the top half's since it is being squashed. We can tell intuitively by looking at the equation above that as we decrease the curvature, we decrease the surface tension.
As you continue to decrease the curvature (squashing your droplet more by adding more water mass) the surface tension will eventually drop below the point needed to maintain the spherical shape and the water will be pushed flat.
This is also known as.... a big mess to clean up.
I Think differently, I agreed every ones ans (which our school taught us that surface tensions and all these all are scientifical parts which is correct but why this all are also happening) ..... not only water drop but every liquid form take shape of spherical, why its not taking shape of square & triangle.......the ans is - Think in this universe every planet, stars are round in shape even our galaxy milky way is rotating in round it self, it means the energy(gravitational or kinetic etc) surrounding in this universe is tend every particle in round shape if we see (for raw materials) or basic material of any particle for eg. Electrons, Nucleus, Cells basic particles its always showed in round.Please mark my brainlist
thank u
The cohesive forces between liquid molecules is responsible for the surface tension. The molecules of water on the surface don't have like molecules around it.So the molecules lying in the surface are attracted or pulled downward by the adjacent water molecules. So the water droplets tend to be pulled into shape of spherical due to cohesive forces.If other forces including gravity is missing,then droplets of all the fluids have spheical shape.So this spherical forms are easier to form, required less surface tension,less wall tension.More the surface tension more will be the spherical form.6.6k Views · View Upvoters · Answer requested by Sharath RajRelated QuestionsMore Answers BelowWhen a water drop falls, does it form a circular shape?Why are rain drop spherical?Why do water drops fall in that shape?Why is the shape of a water drop circular?Why does water form a ball in zero gravity and not another shape?Ask New QuestionGabe Giraldo, Masters in Mechanical EngineeringAnswered Sep 18 2015 · Upvoted by Jerzy Michał Pawlak, PhD in High Energy Physics (experimental)Oh boy! The first question I've seen that I feel confident enough to answer!
We observe the water behaving 2 different ways when placed on a surface, but why? The reason is the surface tension caused by the cohesion of the water molecules.
The two questions we need to answer are:
1. How does surface tension cause a droplet to take the shape that it does?
and
2. Why beyond a "critical point" (such as the cup of water in your example) will it no longer simply form a large droplet shape?
Lets first imagine an ideal sphere of water floating in space. The sphere forms in nature since it is the shape that requires the minimum amount of surface tension to maintain.
Fig 1. Sphere of water.
The sphere has an internal pressure pointing in all directions outward from its center and it also has a surface tension which keeps the water molecules bound in the spherical arrangement.
If we were to cut the droplet such that we have equal left and right halves, we can use Laplace's equation on the circular cross-section to figure out that:
SurfaceTension=InternalPressure∗Radius/2SurfaceTension=InternalPressure∗Radius/2
English Translation: This tells us the minimum surface tension required to support the spherical shape.
Fig 2. Circular cross section of the sphere.
Now lets consider a droplet on a surface. Observation tells us that this is no longer a perfect sphere but a kind of "squashed" sphere which has a wider base along the contact surface.
Fig 3. Droplet on a surface. Note the rounder top vs. the flatter bottom.
Lets divide out droplet now into 2 halves again, left and right halves. This gives us an deformed circular cross section to work with (due to the aforementioned squashing). Now lets divide our new cross-section into top and bottom halves.
Recall that we said the internal pressure points in all directions from the center. This tells us that the pressure in the top half is the same as the pressure in the bottom half. The key difference is that the surface curvature of the bottom half is less than that of the top half's since it is being squashed. We can tell intuitively by looking at the equation above that as we decrease the curvature, we decrease the surface tension.
As you continue to decrease the curvature (squashing your droplet more by adding more water mass) the surface tension will eventually drop below the point needed to maintain the spherical shape and the water will be pushed flat.
This is also known as.... a big mess to clean up.
I Think differently, I agreed every ones ans (which our school taught us that surface tensions and all these all are scientifical parts which is correct but why this all are also happening) ..... not only water drop but every liquid form take shape of spherical, why its not taking shape of square & triangle.......the ans is - Think in this universe every planet, stars are round in shape even our galaxy milky way is rotating in round it self, it means the energy(gravitational or kinetic etc) surrounding in this universe is tend every particle in round shape if we see (for raw materials) or basic material of any particle for eg. Electrons, Nucleus, Cells basic particles its always showed in round.Please mark my brainlist
thank u
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to increase fertility of the soil
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