Fluid Friction and Sliding Friction: Detailed Explanations

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In Everyday life, friction is present in most of activities. The fluid friction and sliding friction can be defined as,

Fluid friction is caused due to the viscous resistance, and sliding friction is caused due to the roughness of the surface.

When two surfaces are in contact with each other, and anyone surface tries to move on the other surface, then one resisting force is raised between them, known as friction

The Irregularities are present because of the roughness of the surface. More roughness means more friction between surfaces, and less roughness means less friction between surfaces.

Now every matter has properties related to friction in different types of manner depending on the phases of matter. Friction in solid is different than friction in any fluid. Now from all these different types of friction, we can divide friction into four types:

Now Friction is everywhere, but we focus on Fluid friction and sliding friction in this article.

Fluid friction vs. sliding friction

Fluid Friction and sliding friction both are types of friction, but there is a small difference between them.

We can say that fluid is made of many layers, and these layers move relatively with each other. Relative velocity is present between all layers of the fluid.

This happens because each layer resists the motion of another layer. This resistance force is known as fluid friction.

fluid friction and sliding friction
Friction Credit Wikipedia

The friction force is offered in fluid because of one property of the fluid, known as Viscosity. Higher viscous force means greater friction, and lower viscous force means lesser friction. So water can move easily on any surface compared to oil.

Examples of fluid friction:

  • When you submerge a spoon in oil or any thick liquid, liquid sticks to the surface of a spoon just because of friction or viscosity.
  • You observe some resistance offered by air while running because of friction produced by air against your running direction.
  • When any two surfaces are trying to slide on eachother, the surface offers the same property to oppose the movement. And this resistance force againstthesliding motion is known as sliding friction.

Examples of sliding friction:

  • We have to give more force to a rough surface than a smooth surface to move any object.
  • We can walk on the road easily without slipping.
  • So we can say that sliding friction occurs on solid surfaces, and fluid friction occurs at fluid layers.

Is fluid friction stronger than sliding friction?

The comparison of fluid friction and sliding friction can be made with following fundamentals,

No, Fluid friction is offered because of the resistance offered by viscosity, and sliding friction is offered because of the roughness of the surface.

Now, If any two mating surfaces are there and we want to move these surfaces with a high velocity with each other. So friction between them should be very less, and for that purpose, we introduce lubricant between them.

The reason to introduce lubricant between them is that lubricant offers low friction and provides smooth working. And lubricant is one type of fluid that means we introduce fluid to decrease the value of friction between two surfaces. It directly states that fluid has less friction than two sliding surfaces have.

So we can say that in comparison of fluid friction and sliding friction. The fluid friction is less stronger than sliding friction

In other ways, Friction is not affected by surface area, but it is just affected by the types of surfaces on which friction is present. And types of surfaces in sliding, friction are solid surfaces, and in fluid, surfaces are liquids or gases. So in fluid, friction surfaces are smooth compared to solid surfaces, and friction is not stronger in fluid than in sliding friction.

Example: We use lubrication in working of I.C. Engine, Power transmission by gear, manufacturing of any part, etc. here, we use lubrication to reduce friction between surfaces of two mating parts. From that, we can achieve less wear and better life of parts.

Is sliding friction stronger than rolling friction?

The sliding friction is due to the resistance offered by any surface.

Yes, The contact surface in sliding friction is flat, and the contact surface in a rolling surface is curved or round. And curved or round surfaces have less tendency to friction than flat surfaces.

Meanwhile, rolling friction has less friction than sliding friction.

Example: If we want to move anybody with a flat surface in contact with another surface, we should use the rolling surface to move that body easily and faster withoutapplying much effort.

Is fluid friction stronger than rolling friction?

The fluid friction is generated due to the resistance offered by fluid layers.

No, Fluid friction is not stronger than rolling friction.

We cannot compare fluid and rolling friction because fluid friction is present in layers of fluid and rolling friction is present in two solid contact surfaces.

Still, if we want to compare, we can say that the weakest friction offered by any type of friction is rolling friction. This means fluid friction is not stronger than rolling friction.

Example: We use balls or rollers in rolling contact bearing instead of oil or lubricant used in sliding contact bearing because rolling contact bearing has less friction than friction produced in fluid-based bearings (oil or lubricant), and rolling contact bearing is also known as Non-friction bearing.

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