13-12-2012, 06:01 PM
Pressure Measurements
Pressure Measurements.ppt (Size: 2.47 MB / Downloads: 238)
Pressure definition
Pressure is the action of one force against another over, a surface. The pressure P of a force F distributed over an area A is defined as:
How Much is a Pascal
A Newton is the force necessary to accelerate a mass of 1 kg at a rate of 1 meter per second per second.
The acceleration of gravity is 9.8 m/sec2
The force due to gravity on a 1 kg mass is 9.8 N is 1 kg weight.
1 Newton is 0.102 kg weight.
How is pressure generated
Collision of molecule with wall
Momentum is mass x velocity
Change of momentum is double
Collision is isothermal = perfectly elastic
Sum collisions over area to get force
Static, dynamic, and impact pressures
Static pressure is the pressure of fluids or gases that are stationary or not in motion.
Dynamic pressure is the pressure exerted by a fluid or gas when it impacts on a surface or an object due to its motion or flow. In Fig., the dynamic pressure is (B − A).
Impact pressure (total pressure) is the sum of the static and dynamic pressures on a surface or object. Point B in Fig. depicts the impact pressure.