FORCES IN FLUIDS

 VISCOSITY

Learning outcome

• To learn about viscosity and viscous force
• To understand how the liquid flow at different rate
• To find out how temperature and viscosity related

INTRODUCTION

Viscosity,resistance of a fluid to a change in shape,or movement of neighbouring portions relative to one another.Viscosity denotes opposition  to flow.

ACTIVITY 1:EXPERIMENT

AIM: To find out whether different liquids have different flow rate.

APPARATUS:Plate,ketchup,mustard,honey,syrup

PROCEDURE:Place one drop each of kerosene, water, glycerin and honey at various points along a straight line at one end of a glass plate. Hold the glass plate slightly tilted. Compare the speed of flow of each liquid.

INFERENCE:Different liquids flow at different speed.

The variation in speed between the layers of liquid is because every layer of liquid opposes the flow of the layer in contact with it.

 

VISCOUS FORCE

Between the layers of a liquid in motion, there is a frictional force parallel to the layers which try to prevent the relative motion between the layers. This frictional force is the viscous

force. 

VISCOSITY

Viscosity is the characteristic property of a liquid to oppose the relative motion between its different layers.

ACTIVTY 2

 Complete the table

Liquids of greater viscosity are the viscous liquids, and those of very lower viscosity are the mobile liquids.

ACTIVITY 3:EXPERIMENT

AIM:To find out how temperature effect on viscosity.

APPARATUS: Cold honey,honey, plate,test tube

PROCEDURE:Take some honey in two test tubes. Heat the honey in one of the test tubes. Then pour different honey at three different points on a glass plate. Tilt the glass plate and observe the flow of the honey.

INFERENCE:Hot honey moves faster than cold honey.

CONCLUSION

Viscosity is the resistance to flow of liquid .Between the layers of a liquid in motion, there is a frictional force parallel to the layers which try to prevent the relative motion between the layers. This frictional force is the viscous force.As temperature increases viscosity decreases.

VIDEOS RELATED TO CLASS

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