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The sections of the ball, the surface area of the ball

Source: licencja: CC 0.

Przekroje kuli, pole powierzchni kuli

Learning objectives

  • You will develop the following competences: communicating in English, mathematical, IT and basic scientific and technical competence, your learning skills.

  • You will get to know the sections of the ball.

  • You will get to know the formula for calculating the surface area of the ball.

Learning effect

  • You will learn the sections of the ball.

  • You will learn how to calculate the surface area of the ball.

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nagranie abstraktu

Recollect all the information about the ballballball that you have already acquired – the method of obtaining the ball and its elements. The aim of the class is calculating the surface area of the ballsurface area of the ballsurface area of the ball and getting to know the sections of the ball. Think about the shape a section of the ballballball has. Compare your ideas to the models. Formulate the conclusion.

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nagranie abstraktu

Any cross sectioncross sectioncross section of the ballballball is a circlecirclecircle.

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nagranie abstraktu

Use any available sources to find the name of the section of the ballballball which passes through the centre of the ball. The section of the ball which passes through the centre of the ball is called the great circle of the ballgreat circle of the ballgreat circle of the ball.

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Source: GroMar, licencja: CC BY 3.0.
Task 1
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nagranie abstraktu

The radius of the ballradius of the ballradius of the ball equals 20 cm. The cross sectioncross sectioncross section of the ballballball was drawn 12 cm away from the great circle of the ballgreat circle of the ballgreat circle of the ball. Calculate the circumference of this section.

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nagranie abstraktu

Analyse the slideshow presenting the formula for the surface area of the ball. Write down the formula.

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Pokaz przedstawia opis powstawania wzoru na pole powierzchni kuli. Instrukcja obsługi z poziomu klawiatury: 1. Uruchomienie aplikacji - ENTER, 2. Na każdym ze slajdów czytany jest automatycznie tekst alternatywny po polsku, 3. Przy pierwszym uruchomieniu na pierwszym slajdzie, czytanie tekstu po angielsku - TAB, 4. Przejście między slajdami: do następnego slajdu - TAB, do poprzedniego slajdu - TAB + SHIFT, 5. Przejście do czytania napisu po angielsku - strzałka w górę + strzałka w dół (czyta tekst po angielsku widoczny na slajdzie).
Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

The formula for the surface area of the ballsurface area of the ballsurface area of the ball:

P=4·π·R2

P – the surface area of the ballsurface area of the ballsurface area of the ball
R – the radius of the ballradius of the ballradius of the ball

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nagranie abstraktu

Look for the relation between the surface areasurface areasurface area of the great circle and the surface area of the ballsurface area of the ballsurface area of the ball. Formulate the conclusion.

The surface area of the ballsurface area of the ballsurface area of the ball is four times bigger than the surface areasurface areasurface area of the great circlecirclecircle.

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nagranie abstraktu

Use the information to do the tasks.

Task 2
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nagranie abstraktu

A part of the ball, whose radiusradiusradius is 8 cm, was cut off 5 cm away from the centre of the ballballball. Calculate the ratio of the section to the area of the great circle of the ballgreat circle of the ballgreat circle of the ball.

Task 3
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nagranie abstraktu

The circle, whose diameterdiameterdiameter is 22 cm, was cut into four identical parts. One of these sectors of the circlecirclecircle was revolved around its radiusradiusradius. Calculate the surface areasurface areasurface area of the obtained solid.

Task 4
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nagranie abstraktu

Two parallel planes cut a ballballball and form two sections, whose surface areas equal 9·π and 36·π respectively. The distance between the planes is 9. Calculate the surface area of the ballsurface area of the ballsurface area of the ball.

Task 5
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nagranie abstraktu

The ratio of the surface areas of two balls is 4, and the difference between their radii is 15 cm. Calculate the radii of these balls.

Task 6
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nagranie abstraktu

The ratio of the diameters of two balls is 6 : 5. What is the ratio of the surface areasurface areasurface area of these balls? Justify your answer.

Task 7

An extra task:

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nagranie abstraktu

Let’s make an assumption that the Earth is a ballballball and the length of the equator is 40000000 m. We surrounded the Earth along the equator with a band measuring 40000100 m. What is the distance between the band and the surface of the Earth?

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nagranie abstraktu

Exercises

Exercise 1
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Wersja alternatywna ćwiczenia: Determine which sentences are true. Możliwe odpowiedzi: 1. The surface area of the ball equals 96π cm2. The radius of the ball has the length of 45 cm., 2. The surface area of the great circle of the ball equals 81π. The surface area of the ball is 324π., 3. If we make the radius of the ball three times larger, the surface area of the ball will be nine times larger. , 4. The diameter of the ball equals 20 cm. The surface area of the ball equals 800π cm2.
zadanie
Source: GroMar, licencja: CC BY 3.0.
Exercise 2

A tent Has a shape of a hemisphere whose radius is 4 m. Calculate how much material you need to buy to make this tent. Assume that π=227. Remember about the material to make the floor, too.

Exercise 3

Describe in English how to calculate the surface area of the ball whose diameter is 7 m.

Exercise 4
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Wersja alternatywna ćwiczenia: Indicate which pairs of expressions or words are translated correctly. Możliwe odpowiedzi: 1. kula - ball, 2. promień kuli - radius of the ball, 3. koło wielkie kuli - great circle of the ball, 4. przekroje kuli - cross sections of the ball, 5. pole powierzchni kuli - hemisphere, 6. półkula - cross sections of the ball
zadanie
Source: GroMar, licencja: CC BY 3.0.
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Interaktywna gra, polegająca na łączeniu wyrazów w pary w ciągu jednej minuty. Czas zaczyna upływać wraz z rozpoczęciem gry. Jeden ruch to odkrywanie najpierw jednej potem drugiej karty z wyrazem. Każdy wyraz jest odczytywany. Kolejny ruch to odkrywanie trzeciej i czwartej karty. W ten sposób odsłuchasz wszystkie wyrazy. Nawigacja z poziomu klawiatury za pomocą strzałek, odsłuchiwanie wyrazów enterem lub spacją. Znajdź wszystkie pary wyrazów.
Source: Zespół autorski Politechniki Łódzkiej, licencja: CC BY 3.0.

Glossary

ball
ball

kula

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wymowa w języku angielskim: ball
circle
circle

okrąg

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wymowa w języku angielskim: circle
cross section
cross section

przekrój poprzeczny

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wymowa w języku angielskim: cross section
diameter
diameter

średnica okręgu

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wymowa w języku angielskim: diameter
great circle of the ball
great circle of the ball

koło wielkie kuli

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wymowa w języku angielskim: great circle of the ball
hemisphere
hemisphere

półkula

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wymowa w języku angielskim: hemisphere
radius
radius

promień

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wymowa w języku angielskim: radius
radius of the ball
radius of the ball

promień kuli

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wymowa w języku angielskim: radius of the ball
surface area
surface area

pole powierzchni

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wymowa w języku angielskim: surface area
surface area of the ball
surface area of the ball

pole powierzchni kuli

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wymowa w języku angielskim: surface area of the ball

Keywords

ballballball

cross sectioncross sectioncross section

great circle of the ballgreat circle of the ballgreat circle of the ball

radius of the ballradius of the ballradius of the ball

surface area of the ballsurface area of the ballsurface area of the ball