Pressure
Content
1.High heeled shoe>Flat school shoe
1.The student would exert less pressure on the ground when she
wears flat school shoe since it has a larger area of contact with the
ground. As the mass of the student is constant, the pressure
exerted is inversely proportional to the area of contact. Therefore,
the pressure exerted by flat school shoe is less.
2.The woman would exert high pressure on the ground when she
wears high heeled shoes since it has a smaller area of contact with
the ground. Therefore, the pressure exerted by high heeled shoe is
higher.
2.Sharp thumbtack>Blunt thumbtack
1. Thumbtack have sharp point so produce a larger pressure. This
pressure easily drives the thumbtack in the wood.
2. Thumbtack have blunt point so produce a smaller pressure. This
pressure difficulty drives the thumbtack in the wood.
3.Pressure in liquid
1. The pressure in a liquid increases with depth.
2. The pressure of water is highest at the lowest point of the
cylinder as the water spurts out the furthest from this point.
4.Hydraulic jacks
1. Hydraulic jacks are used to carry and lift heavy loads.
2. When a small input force is applied to the lever of the jack, a
large output force which is able to lift the load is produced.
5.Boiled egg
1. Once we turn on the pipe water ,the boiled egg will fall down.
2. That is because the pressure transmitted through the liquid.
6.Drinking straw
1. When drinking with a straw, one has to suck the straw. This
causes the pressure in the straw to decrease.
2. The external atmospheric pressure, which is greater, will then act
on the surface of the water in the glass, causing it to rise through
the straw.
7.Syringe
1.A rubber syringe used to draw a liquid from a container.
2.When the piston is pushed to the lowest end, the air inside is forced
out .
3.When the piston is pulled upwards, the air pressure in the cylinder is
reduced.
4.The liquid in the container is forced into the cylinder of the syringe by
the pressure of the atmosphere acting on the surface of the liquid .
8.Siphon
1. A rubber tube can be used to siphon liquid from a container at a
higher level to another at a lower level.
2. The tube is first filled with liquid and one end is placed in the liquid in
container A. The other end is placed at a level which must be lower
than the surface of the liquid in container A.
3. As the pressure at C is greater than the atmospheric pressure, the liquid
flows out at C.
4. The pressure in the rubber tube decreases as the water flows out.
5. The liquid in container A can be completely drained out or flow stops
as soon as the liquid surface in container A is at the same level as C
of the tube.
9.Egg Yolk
1. The volume inside bottle is higher than outside volume.
2. The pressure inside bottle is lower than atmospheric pressure
.Therefore, the atmospheric pressure push the egg yolk into the
bottle.
10.Tyre
1. When we press the tyre with finger, we can feel the impulsive force
to our finger.
2. The impulsive force is because the air pressure cause the gas
molecules inside tyre collides to the container wall .
1. Pressure is defined as the force acting
normally on unit area of a surface.
2. FORMULA P=F/A
3.
The SI unit of pressure is pascal (Pa). It
is equivalent to a force of 1 newton acting
on a surface area of 1 square metre.
4. 1Pa=1Nm-2
5. The pressure exerted by a force on a
surface depends on the force as well as
the area of the surface. The pressure of
a given force increases as the surface
area decreases. Hence, the pressure at
the base of a high-heeled shoe is
greater than that of a flat shoe because
the cross-sectional area of a highheeled shoe is smaller.
6. The pressure on a surface also depends
on the direction the force is applied. If
a force acts at a known angle to a
surface, only the component of the
force which is perpendicular to the
surface is used to determine the
pressure.
1. A liquid in a container exerts
pressure because of its weight. It
also exerts pressure on any object
in it.
2. The pressure at any point in a
liquid acts in all directions. It also
increases with depth because the
deeper the point, the greater the
weight of the liquid above is.
The formula for pressure
in liquid
1. The force acting on the surface
area A is the weight of the
liquid column above it.
Pressure , P =weight of liquid
column /
Area of the base of liquid
column
=W/A
= Ahpg/ A
P = hpg
PRINCIPLE-PRINCIPLE
PRESSURE
OF
Pascal 's principle
The pressure applied to a surface of a fluid in a
confined container is transmitted uniformly in all
directions throughout the fluid.
F /A = F /A
F = Input force
A = Surface area of input cylinder
F = Output force
A = Surface area of output cylinder
Uses: Hydraulic jack, Hydraulic lift, Hydraulic brakes
Archimedes’s Principle
Archimedes (287-212 B.C) was a Greek scientist who
first discovered that when an object is totally or
partically immersed in a fluid, the upthrust or buoyant
force on it is equal to the weight of fluid displaced.
Buoyant force=reduction in weight of object
=weight of fluid displaced
Uses: Ship, Submarine, Hot-air balloon, Hydrometer
Bernoulli’s Principle
In a steady flow of fluid (liquids and gases ) ,the
pressure in the fluid is low when the velocity of the
fluid is high .
Uses: Design of airplanes, Boat hulls, Fan blades, Car ,
Aerofoil, Carburetor, Bunsen burner, Insecticide spray
Example Of Pressure In
Liquid
The water exerts a pressure on the body of the diver so that
the diver discomfort in his body and ears when he dives deep
underwater.
A fire-fighter requires a fire hose for directing a water
jet of very high pressure to put out in a high-rise
building.
Examples Of Atmospheric
Pressure
At higher altitude, the density and temperature of the air are lower,
so the number of collisions between molecules are less and the
pressure is lower.
Atmospheric pressure can be measured by using barometer
mercury, barometer Aneroid and barometer Fortin.
Example Of Archimedes's
Principle
A hot-air balloon rises upwards because the buoyant force acting on it, due to the
surrounding air, is greater than its weight.
Example Of Bernoulli’s
Principle
1.
2.
3.
4.
5.
6.
7.
The air flow over the sail causes an increase in pressure on the
windward side and decrease on the leeward side.
Area of leeward side has a low pressure because of the high
speed of the wind.
A resultant force acts in the direction of F.
This resultant force can be resolved into component to the right
and left.
The component to the right can be balanced by the surfer who
pulls it to the left.
Therefore, there exists a resultant force to the front so that the
surfer moves to the front.
Factors affect the resultant force is the strength of the wind and the
shape of the sail.
Example Of Pascal 's
Principle
1.The student would exert less pressure on the ground when she
wears flat school shoe since it has a larger area of contact with the
ground. As the mass of the student is constant, the pressure
exerted is inversely proportional to the area of contact. Therefore,
the pressure exerted by flat school shoe is less.
2.The woman would exert high pressure on the ground when she
wears high heeled shoes since it has a smaller area of contact with
the ground. Therefore, the pressure exerted by high heeled shoe is
higher.
2.Sharp thumbtack>Blunt thumbtack
1. Thumbtack have sharp point so produce a larger pressure. This
pressure easily drives the thumbtack in the wood.
2. Thumbtack have blunt point so produce a smaller pressure. This
pressure difficulty drives the thumbtack in the wood.
3.Pressure in liquid
1. The pressure in a liquid increases with depth.
2. The pressure of water is highest at the lowest point of the
cylinder as the water spurts out the furthest from this point.
4.Hydraulic jacks
1. Hydraulic jacks are used to carry and lift heavy loads.
2. When a small input force is applied to the lever of the jack, a
large output force which is able to lift the load is produced.
5.Boiled egg
1. Once we turn on the pipe water ,the boiled egg will fall down.
2. That is because the pressure transmitted through the liquid.
6.Drinking straw
1. When drinking with a straw, one has to suck the straw. This
causes the pressure in the straw to decrease.
2. The external atmospheric pressure, which is greater, will then act
on the surface of the water in the glass, causing it to rise through
the straw.
7.Syringe
1.A rubber syringe used to draw a liquid from a container.
2.When the piston is pushed to the lowest end, the air inside is forced
out .
3.When the piston is pulled upwards, the air pressure in the cylinder is
reduced.
4.The liquid in the container is forced into the cylinder of the syringe by
the pressure of the atmosphere acting on the surface of the liquid .
8.Siphon
1. A rubber tube can be used to siphon liquid from a container at a
higher level to another at a lower level.
2. The tube is first filled with liquid and one end is placed in the liquid in
container A. The other end is placed at a level which must be lower
than the surface of the liquid in container A.
3. As the pressure at C is greater than the atmospheric pressure, the liquid
flows out at C.
4. The pressure in the rubber tube decreases as the water flows out.
5. The liquid in container A can be completely drained out or flow stops
as soon as the liquid surface in container A is at the same level as C
of the tube.
9.Egg Yolk
1. The volume inside bottle is higher than outside volume.
2. The pressure inside bottle is lower than atmospheric pressure
.Therefore, the atmospheric pressure push the egg yolk into the
bottle.
10.Tyre
1. When we press the tyre with finger, we can feel the impulsive force
to our finger.
2. The impulsive force is because the air pressure cause the gas
molecules inside tyre collides to the container wall .
1. Pressure is defined as the force acting
normally on unit area of a surface.
2. FORMULA P=F/A
3.
The SI unit of pressure is pascal (Pa). It
is equivalent to a force of 1 newton acting
on a surface area of 1 square metre.
4. 1Pa=1Nm-2
5. The pressure exerted by a force on a
surface depends on the force as well as
the area of the surface. The pressure of
a given force increases as the surface
area decreases. Hence, the pressure at
the base of a high-heeled shoe is
greater than that of a flat shoe because
the cross-sectional area of a highheeled shoe is smaller.
6. The pressure on a surface also depends
on the direction the force is applied. If
a force acts at a known angle to a
surface, only the component of the
force which is perpendicular to the
surface is used to determine the
pressure.
1. A liquid in a container exerts
pressure because of its weight. It
also exerts pressure on any object
in it.
2. The pressure at any point in a
liquid acts in all directions. It also
increases with depth because the
deeper the point, the greater the
weight of the liquid above is.
The formula for pressure
in liquid
1. The force acting on the surface
area A is the weight of the
liquid column above it.
Pressure , P =weight of liquid
column /
Area of the base of liquid
column
=W/A
= Ahpg/ A
P = hpg
PRINCIPLE-PRINCIPLE
PRESSURE
OF
Pascal 's principle
The pressure applied to a surface of a fluid in a
confined container is transmitted uniformly in all
directions throughout the fluid.
F /A = F /A
F = Input force
A = Surface area of input cylinder
F = Output force
A = Surface area of output cylinder
Uses: Hydraulic jack, Hydraulic lift, Hydraulic brakes
Archimedes’s Principle
Archimedes (287-212 B.C) was a Greek scientist who
first discovered that when an object is totally or
partically immersed in a fluid, the upthrust or buoyant
force on it is equal to the weight of fluid displaced.
Buoyant force=reduction in weight of object
=weight of fluid displaced
Uses: Ship, Submarine, Hot-air balloon, Hydrometer
Bernoulli’s Principle
In a steady flow of fluid (liquids and gases ) ,the
pressure in the fluid is low when the velocity of the
fluid is high .
Uses: Design of airplanes, Boat hulls, Fan blades, Car ,
Aerofoil, Carburetor, Bunsen burner, Insecticide spray
Example Of Pressure In
Liquid
The water exerts a pressure on the body of the diver so that
the diver discomfort in his body and ears when he dives deep
underwater.
A fire-fighter requires a fire hose for directing a water
jet of very high pressure to put out in a high-rise
building.
Examples Of Atmospheric
Pressure
At higher altitude, the density and temperature of the air are lower,
so the number of collisions between molecules are less and the
pressure is lower.
Atmospheric pressure can be measured by using barometer
mercury, barometer Aneroid and barometer Fortin.
Example Of Archimedes's
Principle
A hot-air balloon rises upwards because the buoyant force acting on it, due to the
surrounding air, is greater than its weight.
Example Of Bernoulli’s
Principle
1.
2.
3.
4.
5.
6.
7.
The air flow over the sail causes an increase in pressure on the
windward side and decrease on the leeward side.
Area of leeward side has a low pressure because of the high
speed of the wind.
A resultant force acts in the direction of F.
This resultant force can be resolved into component to the right
and left.
The component to the right can be balanced by the surfer who
pulls it to the left.
Therefore, there exists a resultant force to the front so that the
surfer moves to the front.
Factors affect the resultant force is the strength of the wind and the
shape of the sail.
Example Of Pascal 's
Principle
