Topicm318ef4b24f4bbe81_1528449000663_0Topic

How much pressure do you exert?

Levelm318ef4b24f4bbe81_1528449084556_0Level

Second

Core curriculumm318ef4b24f4bbe81_1528449076687_0Core curriculum

Using physical concepts and quantities to describe phenomena and to indicate their examples in the surrounding reality.

V. Matter's properties. The student:

3) uses the concept of normal force and the concept of pressure in liquids and gases along with its unit; applies the relationship between normal force and pressure to the calculation;

4) uses the concept of atmospheric pressure.

Timingm318ef4b24f4bbe81_1528449068082_0Timing

45 minutes

General learning objectivesm318ef4b24f4bbe81_1528449523725_0General learning objectives

Recognizing pressure measurement methods and measuring instruments.

Key competencesm318ef4b24f4bbe81_1528449552113_0Key competences

1. Recognizing pressure measuring instruments.

2. Determining the pressure value in communicating vessels.

Operational (detailed) goalsm318ef4b24f4bbe81_1528450430307_0Operational (detailed) goals

The student:

- identifies instruments used to measure pressure,

- specifies the value of pressure in the communicating vessels.

Methodsm318ef4b24f4bbe81_1528449534267_0Methods

1. Learning by observation.

2. Teaching by solving empirical problems.

Forms of workm318ef4b24f4bbe81_1528449514617_0Forms of work

1. Individual work.

2. Work with the whole class.

Lesson stages

Introductionm318ef4b24f4bbe81_1528450127855_0Introduction

Task 1

Answer the questions:

a) What is the pressure?
b) Provide the formula for calculating the pressure.
c) What determines the hydrostatic pressure?
d) What is the formula for calculating the hydrostatic pressure?
e) What determines the atmospheric pressure?
f) What is the unit of the pressure in the SI system?

Answer:

a) The pressure is the physical quantity that informs us how much force is applied perpendicular to the surface unit.
b) The pressure is equal to the quotient of the normal force and the surface area.
c) The pressure due to the weight of the non‑moving (static) fluid is called hydrostatic pressure.
d) The formula for calculating the hydrostatic pressure is p=d·g·h.
e) Atmospheric pressure is the pressure exerted by the atmosphere on the bodies within the atmosphere or on the surface of the Earth. Atmospheric pressure - like hydrostatic pressure - is related to the weight of the air above the level at which we measure the pressure. The closer to the Earth's surface, the higher the atmospheric pressure, and conversely - it is lower on mountain peaks than in the valleys.
f) The basic pressure unit in the SI system is pascal (1 Pa).
m318ef4b24f4bbe81_1527752263647_0a) The pressure is the physical quantity that informs us how much force is applied perpendicular to the surface unit.
b) The pressure is equal to the quotient of the normal force and the surface area.
c) The pressure due to the weight of the non‑moving (static) fluid is called hydrostatic pressure.
d) The formula for calculating the hydrostatic pressure is p=d·g·h.
e) Atmospheric pressure is the pressure exerted by the atmosphere on the bodies within the atmosphere or on the surface of the Earth. Atmospheric pressure - like hydrostatic pressure - is related to the weight of the air above the level at which we measure the pressure. The closer to the Earth's surface, the higher the atmospheric pressure, and conversely - it is lower on mountain peaks than in the valleys.
f) The basic pressure unit in the SI system is pascal (1 Pa).

Procedurem318ef4b24f4bbe81_1528446435040_0Procedure

[Slideshow 1]

Task 1

Answer the question:

In which units can we give the pressure value?

Answer:

The pressure can be given in such units as:

- atmosphere - atm,
- millimeters of mercury - mm Hg,
- pascal - Pa.

The relationship between these pressure units:

1atm=760mmHg=1013,25hPa=101325Pa

[Interactive graphics]

Task 2

Answer the questions:

a) What are the main elements of an aneroidaneroidaneroid?
b) How the aneroid works?
c) What other pressure measuring instruments do you know?

Answer:

a) Hand‑set pointer, pointer, lever, flexible metal box.
b) The flexible metal box moves the lever when the pressure changes. The lever movement causes the spindle of the pointer to rotate. In order to recognize whether the pressure increased or decreased, the pointer is compared to the hand‑set pointer.
c) Torricelli's mercury barometerbarometerbarometer, analogue barometer, electronic barometer.

Task 4

Convert units:

a) 780 mm Hg to pascal and hectopascal,
b) 980 Pa to mm Hg.

Answer:

a) 1atm=760mmHg=1013,25hPa, therefore:

780mmHg=780mmHg101325Pa760mmHg=103991Pa=1039,91hPa

b) 980Pa=980Pa760mmHg101325Pa=7,351mmHg

[Illustration 1]

The liquid level in the communicating vesselscommunicating vesselscommunicating vessels is always the same.

The pressure measured at the same depth in each of the arms is the same. This fact results from the dependence on the hydrostatic pressure p at depth h in the liquid with the density d in the gravitational field of the Earth with the standard gravity g=9,81ms2:

p=d·g·h

Task 5

Take a look at the pictures and familiarize with the system of communicating vesselscommunicating vesselscommunicating vessels.

[Illustration 1]

Task 6

Watch the slideshow Lock gates, this is an example of the application of the principle of balance out liquid levels in the system of communicating vessels.m318ef4b24f4bbe81_1527752256679_0Watch the slideshow Lock gates, this is an example of the application of the principle of balance out liquid levels in the system of communicating vessels.

[Slideshow 2]

Task 7

Evaluate whether the sentences below are true or false:

a) The pressure unit in the SI system is mm Hg.
b) The pressure unit in the SI system is pascal (Pa).
c) The locklocklock lifting boats operates on the principle of a communicating vessel system.
d) The aneroidaneroidaneroid can measure changes in the atmospheric pressure

Answer:

a) False. b) True. c) True. d) True.

Lesson summarym318ef4b24f4bbe81_1528450119332_0Lesson summary

One of the first instruments to measure atmospheric pressure was the mercury barometerbarometerbarometer.

The pressure exerted by the 760 mm of mercury is one atmosphere.

1atm=760mmHg=1013,25hPa=101325Pa

Currently, we use barometers, or aneroids, to measure atmospheric pressure.

The pressure of gases and liquids is measured using manometers.

Communicating vessels are a system of several vessels, usually of different shapes, connected in such a way that liquid can flow freely between them. The principle of communicating vessels is used in water supply systems and water locks.

Selected words and expressions used in the lesson plan

aneroidaneroidaneroid

barometerbarometerbarometer

communicating vesselscommunicating vesselscommunicating vessels

level of the liquidlevel of the liquidlevel of the liquid

locklocklock

Torricelli barometerTorricelli barometerTorricelli barometer

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Torricelli barometer1
Torricelli barometer

barometr Torricellego

RtPzoePShbXvE
wymowa w języku angielskim: Torricelli barometer
communicating vessels1
communicating vessels

naczynia połączone

RXgDpU1TE6siL
wymowa w języku angielskim: communicating vessels
aneroid1
aneroid

aneroid

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wymowa w języku angielskim: aneroid
barometer1
barometer

barometr

RBo9zedNS7fTU
wymowa w języku angielskim: barometer
lock1
lock

śluza

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wymowa w języku angielskim: lock
level of the liquid1
level of the liquid

poziom cieczy

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wymowa w języku angielskim: level of the liquid