Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 11

# Water Near the Bed of a Deep River is Quiet While that Near the Surface Flows. Give Reasons. - Physics

Short Note

Water near the bed of a deep river is quiet while that near the surface flows. Give reasons.

#### Solution

The motion of any liquid is dependent upon the amount of stress acting on it. The motion of one layer of liquid is resisted by the other due to the property of viscosity. A river bed remains in a static state. Therefore, any immediate layer of liquid in contact with the river bed will also remain static due to the frictional force. However, the next layer of liquid above this static layer will have a greater velocity due to lesser resistance offered by the static layer. Moving upwards, subsequent layers provide lesser and lesser resistance to the movement of the layers above it. Finally, the topmost layer acquires the maximum velocity. Therefore, for a river, the surface waters flow the fastest .

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#### APPEARS IN

HC Verma Class 11, 12 Concepts of Physics 1
Chapter 14 Some Mechanical Properties of Matter
Short Answers | Q 18 | Page 298