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What is viscous drag Class 11?
Hint: Viscous drag is a force between any two layers of flowing liquid, when there is a relative motion between the two layers. The viscous drag opposes the relative motion between the two layers. The magnitude of the viscous drag is given as F=ηAdvdy.
What causes viscous drag?
Surface area is not important when one is dealing with pressure drag, but it is important when dealing with viscous drag — drag caused by layers of the fluid sticking to the object and to one another. More surface area means more of the object is in contact with the fluid, which means more drag.
Is viscous drag same as drag force?
The viscous force on a surface is one of those components of drag. Viscous is used for both liquids and gases. Form drag is the part of the drag force that comes in when the body converts “dynamic pressure/kinetic energy” of the fluid flowing by to static pressure at its leading bluff edge.
What is viscous drag formula?
He found what has become known as Stokes’ Law: the drag force F on a sphere of radius a moving through a fluid of viscosity η at speed v is given by: F=6πaηv. Note that this drag force is directly proportional to the radius.
What is viscous drag Class 12?
viscous drag: a resistance force exerted on a moving object, with a nontrivial dependence on velocity terminal speed: the speed at which the viscous drag of an object falling in a viscous fluid is equal to the other forces acting on the object (such as gravity), so that the acceleration of the object is zero.
What is meant by viscous drag Class 7?
Viscous drag is caused due to viscosity of fluid. Viscosity is resistance of fluids (liquids and gases) to flow. If a fluid is in laminar flow around an obstacle, it exerts viscous drag on that obstacle.
How does viscosity affect drag?
Drag force arises when an object moves through a fluid or, equivalently, when fluid flows past an object. In general, the drag force grows larger with increased flow velocity, but viscosity is a complex phenomenon that cannot be reduced to the simple relationship “drag force is proportional to velocity”.
What is B in drag force?
So, the shape of the object influences the value of “b”, the density of the fluid influences “b”, and so on. This means that we can write the air resistance force (or drag force) as fdrag = bv for very small, slow objects, or fdrag = bv2 for “human-size objects, depending on the situation.
What is Stoke’s law in physics?
Stokes’ law is a law in physics that states that the force that resists a sphere’s fall in a viscous fluid is directly proportional to the velocity of the sphere, the radius of the sphere, and the viscosity of the fluid. r is the radius of the sphere.
How is the drag force related to viscosity?
Viscosity and drag Drag force arises when an object moves through a fluid or, equivalently, when fluid flows past an object. In general, the drag force grows larger with increased flow velocity, but viscosity is a complex phenomenon that cannot be reduced to the simple relationship “drag force is proportional to velocity”.
What kind of drag is in a fluid?
Drag is essentially friction in fluid mechanics. A body moving through a fluid experiences an opposing force similar to a box sliding over the ground experiences friction. Viscous drag corresponds to this in particular. However there are many other types of drag in aerodynamics.
What is the Reynolds number for viscous drag?
The Reynolds number, Re,b is given by where l is a reference length, usually the length of the object parallel to the flow. The Reynolds number represents the ratio of inertial forces to viscous forces ( Fox and McDonald, 1998, p. 306 ).
What’s the difference between skin friction and viscous drag?
At low Reynolds numbers, in contrast, viscous drag dominates, and the alternate name of this form of drag is skin friction drag for a reason. The more surface area an object has, the more viscous drag it will produce.