5.6
07 October 2011
10:40
· 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
5.5 Demo 2 - Collapsing Bottle
12 October 2011
07:19
· Collapsing Bottle
· 5.5 understand that the pressure at a point in a gas or liquid which is at rest acts equally in all directions
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· PFY p.91, Q.3 and 7.
p= F/A
100 000 = F/10
100 000 X 10 = 1000000N
a) p= F/A
p= 500/0.0005
p= 100 000Pa
b) p= F/A
100 000= F/0.002
A= 2 000N
Density of a regular solid – Lead
Mass = 175.4g
Width = 2cm
Length = 5cm
Height = 4.6cm
Volume = width x length x height
V = 2 x 5 x 4.6 = 46cm3
P = m / V = 175.4 / 46 = 12.5g/cm3
