1. It is the pressure exerted on small element by the fluid particles in the region around, not the external pressure used to move the fluid 2.since it is pressure, on both sides, the direction must be towards the element (pushing the element) 3. We have considered the fuild particles (mass) only in the small element, i.e.ds. hence it starts at zero in the left end and keep on increasing towards right hence the term, (rho (pressure)/rho(distance) × element distance, ds ) is added to the right end. Hope it clears your doubt
1. It is the pressure exerted on small element by the fluid particles in the region around, not the external pressure used to move the fluid 2.since it is pressure, on both sides, the direction must be towards the element (pushing the element) 3. We have considered the fuild particles (mass) only in the small element, i.e.ds. hence it starts at zero in the left end and keep on increasing towards right hence the term, (rho (pressure)/rho(distance) × element distance, ds ) is added to the right end. Hope it clears your doubt
In order to derive a concept we have to consider all possible features, so we assume that the pressure is increasing while the fluid is flowing through the control volume.
One more thing, always the external forces accelerate the objects (F=ma Newton's second law of motion) so the pressure is increased after traveling ds distance.
1. It is the pressure exerted on small element by the fluid particles in the region around, not the external pressure used to move the fluid 2.since it is pressure, on both sides, the direction must be towards the element (pushing the element) 3. We have considered the fuild particles (mass) only in the small element, i.e.ds. hence it starts at zero in the left end and keep on increasing towards right hence the term, (rho (pressure)/rho(distance) × element distance, ds ) is added to the right end. Hope it clears your doubt
Why we not consider shear sir.? We consider newtons 2nd law its ok because of motion. 3rd law is there is equal and opposite reaction.. how can pressure force in cylindrical body will be negative..?
1. It is the pressure exerted on small element by the fluid particles in the region around, not the external pressure used to move the fluid 2.since it is pressure, on both sides, the direction must be towards the element (pushing the element) 3. We have considered the fuild particles (mass) only in the small element, i.e.ds. hence it starts at zero in the left end and keep on increasing towards right hence the term, (rho (pressure)/rho(distance) × element distance, ds ) is added to the right end. Hope it clears your doubt
