the properties of fluids: more practice. pressure: student success criteria i can solve problems and...
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The Properties of Fluids: The Properties of Fluids: More PracticeMore Practice
The Properties of Fluids: The Properties of Fluids: More PracticeMore Practice
The Properties of Fluids: The Properties of Fluids: More PracticeMore Practice
Pressure: Student Success Pressure: Student Success CriteriaCriteriaI can solve problems and conduct
an investigation related to the relationships between force, area, pressure, and volume.
An Introduction to An Introduction to PressurePressureSPH4C
PressurePressure
Pressure is defined as the magnitude of the force per unit area:
A
Fp
PressurePressure
Pressure is defined as the magnitude of the force per unit area:
Pressure therefore has units of N/m2
A
Fp
PressurePressure
Pressure is defined as the magnitude of the force per unit area:
Pressure therefore has units of N/m2, or pascals (Pa).
A
Fp
1 pascal1 pascal
1 Pa is approximately equal to the pressure exerted by a single sheet of newspaper spread out on the floor.
1 pascal1 pascal
1 Pa is approximately equal to the pressure exerted by a single sheet of newspaper spread out on the floor.
Most pressures are therefore given in kilopascals (kPa):
1 Pa = 0.001 kPa
ExampleExample
A crate is 2.0 m long and 1.0 m wide. The weight of the crate is 5.2 x 103 N. What pressure does the crate exert on the floor?
ExampleExample
A crate is 2.0 m long and 1.0 m wide. The weight of the crate is 5.2 x 103 N. What pressure does the crate exert on the floor?
ExampleExample
A crate is 2.0 m long and 1.0 m wide. The weight of the crate is 5.2 x 103 N. What pressure does the crate exert on the floor?
ExampleExample
A crate is 2.0 m long and 1.0 m wide. The weight of the crate is 5.2 x 103 N. What pressure does the crate exert on the floor?
kPaor
Pam
N
A
Fp
NF
mmmwlA
6.2
106.20.2
102.5
102.5
0.20.10.2
32
3
3
2
Atmospheric pressureAtmospheric pressure
The weight of the layers of air above us exerts a pressure.
Atmospheric pressureAtmospheric pressure
Standard atmospheric pressure at sea level is 101.3 kPa (or 1 atmosphere).
This instrument used to measure air pressure is called a barometer.
Atmospheric pressureAtmospheric pressure
A drinking straw works by decreasing the air pressure inside the straw: the atmospheric pressure is then greater than that in the straw and forces the liquid to rise up in the straw.
Atmospheric pressureAtmospheric pressureAtmospheric pressure decreases at
higher altitudes as there is less air above you.
Atmospheric pressureAtmospheric pressureAtmospheric pressure decreases at
higher altitudes as there is less air above you.
This can cause your ears to “pop” when the pressure inside your ears is greater than the pressure outside.
Water PressureWater Pressure
Similarly pressure will increase with increasing depth under water as you have more water above you.