Question:
The tangential force (or) viscous force on any layer of the liquid is directly proportional to velocity gradient $\left(\frac{dv}{dx}\right)$ . Then the direction of velocity gradient is :
The tangential force (or) viscous force on any layer of the liquid is directly proportional to velocity gradient $\left(\frac{dv}{dx}\right)$ . Then the direction of velocity gradient is :
Updated On: Aug 1, 2022
- Perpendicular to the direction of flow of liquid
- Parallel to the direction of flow of liquid
- Opposite to the direction of flow of the liquid
- independent of the direction of flow of liquid
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The Correct Option is A
Solution and Explanation
According to question tangential force, $F _{ T } \propto \frac{ dV }{ dX }$
Now, because of viscous force, liquid which is in contact with the surface does not move and the liquid of the top layer moves with greater velocity, so there is velocity change in vertical direction. Thus $\frac{ dV }{ dX }$ is perpendicular to the direction of flow of liquid.
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Concepts Used:
Pressure
Pressure is defined as the force applied perpendicular to the surface of an object per unit area over which that force is distributed.
Everyday examples of pressure are:
- The working of the vacuum cleaner is an example of pressure. The fan inside the vacuum creates a low-pressure region which makes it easy to suck the dust particles inside the vacuum.
- Using a knife for cutting is another example of pressure. The area exposed from the knife is small but the pressure is high enough to cut the vegetables and fruits.
Formula:
When a force of ‘F’ Newton is applied perpendicularly to a surface area ‘A’, then the pressure exerted on the surface by the force is equal to the ratio of F to A. The formula for pressure (P) is:
P = F / A
Units of Pressure:
The SI unit of pressure is the pascal (Pa)
A pascal can be defined as a force of one newton applied over a surface area of a one-meter square.