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igcse physics notesprinted 70 · PDF 70
124 pagesrevision 46936
printed 70 · PDF 70
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70
Since the downwards force(weight) is constant while the area
has increased, the total pressure exerted on the ground is less
so the ice is much less likely to break.
(B)Pressure in solids=Force/Area
Pressure in fluid= Density x Gravitational field strength x height below the surface
of liquid OR P=ρgh
The pressure on point X will be equal to the sum of the pressure exerted by the
ice and the water both because both the ice and the water are exerting pressure
at that point.
Pressure on point X= Pressure of ice + Pressure of water
Pressure of ice= Weight/Area of pond
Pi=690 x 9.81/5.0 ∴ Pi= 1353.78 Pa
Pw= 1000 x 9.81 x 0.45 ∴ Pw= 4414.5 Pa
Pressure at X= 1353.78+4414.5 = 5768.28 Pa
PX= 5800 Pa rounded off to two significant figures
(c) Pressure in liquids= ρgΔh
Pressure at top=0
Pressure at bottom= 1000 x 9.81 x 40/100 = 3900 Pa
Pressure difference=3900-0 = 3900 Pa
3)
(a)(i) When the temperature of the bottle and its contents is increased, the air
particles inside the bottle gain more kinetic energy. They move faster and have
more forceful and frequent collisions. Thus, they exert more force per unit area
leading to a greater change in momentum as well.
Since pressure is force per unit area OR rate of change of momentum per unit
area, the pressure will increase while the volume remains unchanged.
(a)(ii) When the bottle and its contents were heated, pressure increased and
became greater than the outside pressure(atmospheric pressure). So when the
lid is removed air particles will move from higher to lower pressure and pressure
inside the bottle will decrease.
Statement: The air pressure will decrease.
Explanation: Air will move out of the bottle from higher to lower pressure, until
the air pressure inside the bottle is equal to the air pressure outside the bottle.