How to convert mesh no to screen opening in mm? Have been looking for an answer for long time but with no success.

Can atmospheric pressure can be greater than 760 mmHg at sea level or it is always less than 760 mmHg.

explain the difference between shear force,viscous force,skin friction(or wall drag)

If we consider the flow in pipes,is shear force acting is same as viscous force also even skin friction(wall drag). If different explain the difference between shear force,viscous force,skin friction(or...