2 Pressure

Question 1

Pressure units for
1N/m2
1000N/m2
1 bar

Answer 1

1 Pa
1kPa
100kPa

Question 2

Units for the following in N/m2
1 Pa
1kPa
100kPa

Answer 2

1N/m2
1000N/m2
1 bar

Question 3

Net force in the X direction (dP/dx) on a small cube of dimension dxdydz for fluid at rest

Answer 3

0, dP/dx=0 in x direction

Question 4

Net force in the Y direction (dP/dy) on a small cube of dimension dxdydz for fluid at rest

Answer 4

0, dP/dy=0 in xydirection

Question 5

Net force in the Z direction (dP/dz) on a small cube of dimension dxdydz for fluid at rest

Answer 5

dP/dz + gamma =0
gamma=pg
????

Question 6

What do we assume when the fluid is incompressible and homogenous?

Answer 6

P density is contant

Question 7

What do we assume when the fluid is p= constant density?

Answer 7

fluid is incompressible and homogenous

Question 8

P of a point on the water’s surface exposed to outside air?

Answer 8

P=atm
=1 bar (absolute)
=0 (gauge)

Question 9

Pgauge of a point

Answer 9

Pgauge= pgh (NO ATM as Patm is taken to be 0)

Question 10

Pabs of a point

Answer 10

Pabs= Pgauge + Patm
can be pos or neg depending on whether Pgauge or Patm is larger

Question 11

Pressure head

Answer 11

P/pg (m)

Question 12

Pizometric head

Answer 12

P/pg + Z (elevation above datum) (m)

Question 13

Pressure gauge for multiple layers of liquid

Answer 13

sum of pgh of each zone

Question 14

Gamma

Answer 14

pg

Question 15

Cavitation Number

Answer 15

sigma = (P-Pv)/(1/2pv^2)