5.6

5.6 recall and use the relationship for pressure difference:

 

        pressure difference = height × density × g

                               ∆p = h × ρ × g

 

 

∆p = pressure of the fluid (N/m² or Pa)

h = height of the fluid (m)

ρ = density of the fluid (kg/m³)

g = gravitational field strength (N/kg)

 

 

5.6 Demo - squirting water column

12 October 2011

07:24

·         The bottom hole squirts water the furthest

·         Because the water at the bottom has the greatest pressure

·         Because in the formula ∆p = h × ρ × g, ρ is constant, g is constant and h is large

·         So ∆p = large

 

 

5.6 Questions

07 October 2011

11:53

Collins, p.107

Q.5)

pressure difference=height*density*g

(250 000-100 000)=x*1000*10

150 000/10 000=x

15m=x (height)

Yes, because fresh water is denser then fresh water, therefore increasing the answer slightly

Q.6)

P=h*p*g

(1600 mbar=160 000Pa)

160 000-x=50*0.42*1.4

x=29.4

Total pressure

=29.4+160 000

Correction

0.42cm3=420m3

50*450*1.4

=29 400

Total Pressure

=29 400+160 000

=189,000Pa

DONT FORGET TO CHECK UNITS!!!!!!!!!!!!!!

Notes:

ρ_{fresh water} = 1,000kg/m³

g = 10N/kg

1,000mbar = 1 bar = 100,000Pa

 

 

 

5.6 Plenary

12 October 2011

07:23

·         Which diver experiences the greatest pressure?