I can better put my doubt in form of problem:
The temperature of a gas placed in an open container is raised from $27^o$ C to $227^o$ C. The percent of the original amount of the gas expelled from the container will be:
Now in the solution we apply ideal gas equation and say that pressure remains...
Suppose we have a fluid in contact with a surface. By "fluid" I mean anything that can flow so it could be a gas or a liquid. The same argument applies to both.
If the forces are not normal to the surface that means the force the surface exerts on the fluid will have some horizontal component i.e. a component parallel to the surface. Yes?
But the fluid can flow, so if there is any component of force parallel to the surface than the fluid will flow parallel to the surface. That means what I've drawn above cannot be the situation at equilibrium.
If the forces looked like that the fluid would start to flow, and it would continue to flow until the force became normal to the surface.
In my diagram I drew the surface horizontal because that made a nice clear diagram. I could have drawn the surface at any angle. Whatever the angle of the surface the force created by the fluid at the surface must be normal to the surface, because if it wasn't we'd get fluid flow parallel to the surface.
So if the surface is vertical the force created by the fluid on the surface must be horizontal.
Also , the way you told me sir . Then we can draw horizontal components right . Those horizontal components will also be to each other due to Newton’s third law . Fssintheta = Ffsintheta
What do you think about this sir
If the horizontal components are equal , then fluid is not flowing and horizontal components are also perpendicular
If there is a horizontal component of the force the fluid exerts on the surface then there will be an equal and opposite horizontal component of the force the surface exerts on the fluid:
But the two parallel forces do not cancel each other out because they are acting on different objects. The red force acts on the fluid while the blue force acts on the solid.
The parallel forces would only cancel if they were both acting on the same object, but this is not the case.
If you have a metal sphere and you put pressurised fluid inside it then the metal cannot flow away from the fluid inside it and get bigger because, well, it's a solid.
The forces would be pushing the water into the centres of the faces of the cube, and that would compress the water and increase its pressure. Since the pressure at the centre of the faces would then be higher than the pressure in the rest of the container fluid would flow away from the centres of the faces out into the rest of the fluid.
