Q.Define clearly coefficient of viscosity and find its dimensions.
Viscosity.When the motion of a liquid over a horizontal solid surface is slow and steady,its layer in contact with the solid surface is stationary .In other words,its velocity along the surface is zero.The velocity of any other layer is proportional to its distance from the stationary layer and is maximum for the top-most layer.
if we consider any particular layer of the liquid,we find that the layer immediately above.it is moving faster than the layer immediately below it.
Hence the upper layer tends to increase the velocity of the lower layer whereas the lower layer tends to decrease the velocity of the upper layer.The two layers together tend to destroy their relative motion as if there is some backward dragging force acting tangentially on the layers.Consequently,if a relative velocity is to be maintained between the two layers of a liquid,an external force is required to overcome this backward drag.
This property by virtue of which a liquid opposes relative motion between its different layers is called viscosity.
Coefficient of viscosity.Let a layer RS of a liquid move with velocity v relative to a parallel layer PQ which is at a distance r from it.Let the force on an area A required to produce this motion be F.This force must act on RS in the direction of motion.An equal force will,therefore ,act on it in the opposite direction due to viscosity.
This backward dragging force F depends upon the following factors:
Viscosity.When the motion of a liquid over a horizontal solid surface is slow and steady,its layer in contact with the solid surface is stationary .In other words,its velocity along the surface is zero.The velocity of any other layer is proportional to its distance from the stationary layer and is maximum for the top-most layer.
if we consider any particular layer of the liquid,we find that the layer immediately above.it is moving faster than the layer immediately below it.
Hence the upper layer tends to increase the velocity of the lower layer whereas the lower layer tends to decrease the velocity of the upper layer.The two layers together tend to destroy their relative motion as if there is some backward dragging force acting tangentially on the layers.Consequently,if a relative velocity is to be maintained between the two layers of a liquid,an external force is required to overcome this backward drag.
This property by virtue of which a liquid opposes relative motion between its different layers is called viscosity.
Coefficient of viscosity.Let a layer RS of a liquid move with velocity v relative to a parallel layer PQ which is at a distance r from it.Let the force on an area A required to produce this motion be F.This force must act on RS in the direction of motion.An equal force will,therefore ,act on it in the opposite direction due to viscosity.
This backward dragging force F depends upon the following factors:
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