Hundreds of years ago, it was believed that the Earth is flat and if it was spherical humans living on the opposite side would fall off. In reality this does not happed because each body is acted upon by the gravitational force connected with gravity. It’s a force exerted by the Earth to attract all that’s on or near it.
R1rZIEyOSFg58
Ilustracja prezentuje kulę ziemską, na której stoją cztery sylwetki człowieka umiejscowione w punktach północ (góra), południe (dół), wschód (prawa strona), zachód (lewa strona).
The effects of gravitational force. The Earth's gravitational force attracts all objects regardless of their position relative to the planet
Source: 7854, Dariusz Adryan, http://pixabay.com, licencja: CC BY 3.0.
Lets check whether gravity acts on all objects the same way. Perhaps items with a greater mass are attracted with greater force?
Gravitational force
Observation 1
Checking how gravity affects different objects.
You will need
several items with a different mass, but a small surface, e.g. a football, pingpong ball, box of matches, pencil, paper clip.
Instruction
Grab any two objects.
Drop them from the same height and let them fall to the ground. Which of them dropped faster?
Repear the observation using different objects.
Repeat the observation, but this time drop objects from greater height, e.g. by standing on a chair.
Summary
If you drop two objects at the exact same time, they will hit the floor at the same time.
RN2MUfbHYdq78
Ilustracja przedstawia dwie dziewczynki. Jedna stoi na drabinie i wypuszcza z rąk dwie kule - mniejszą i większą. Obie kule spadają na podłogę z tą samą prędkością, równo. Druga dziewczynka asekuruje koleżankę stojącą na drabinie.
Studies on the effects of gravity. The force of gravity affects all objects in the same way, which means that they fall to Earth at the same time
Source: Andrzej Bogusz, licencja: CC BY 3.0.
The gravitational force is exerted by each object – the Earth, but also the Moon and the Sun. The greater the body mass, the higher the gravity. The Moon is significantly smaller than the Earth – that’s why gravity there is six time weaker. Gravity allows us to live anywhere on Earth without the risk of anyone falling off. Owing to gravity, the Moon and artificial satellites also orbit the Earth.
R1OFO79a6Q37I
Fotografia prezentuje statek kosmiczny poruszający się w przestrzeni okołoziemskiej. Satelita ma kształt cylindra z przewężeniem w okolicach połowy jego długości. Po bokach satelity wystają prostokątne baterie słoneczne.
Spacecraft. The space ship is moving at great speed and could fly into space. It does not allow him to do the force of gravity, which makes the vehicle will be circling around the Earth
Fotografia prezentuje panoramę szerokiego i głębokiego wklęśnięcia w Ziemi nazywanego kraterem.
Crater. In space, there are rock fragments of various sizes. When they are close enough to the Earth, the force of its gravity can change their course, and as a result they will fall to the surface of our planet. If such a rock is large, then the force of the impact will make a crater in the place of fall
Source: Patrick Finnegan, www.flickr.com, licencja: CC BY 2.0.
Important!
If you apply appropriate force, it’s possible to overcome gravity. For instance, birds take flight using the strength of their own muscles. Powerful rocket engines allow to launch spacecraft far enough so that Earth’s gravity no longer affects them. Such craft can move away from Earth.
R13A8DXoMvXUT
Ilustracja interaktywna - trzy fotografie. 1. Na zdjęciu dziewczynka skacze na trampolinie. Jump on the trampoline while bending your knees and waving your hands and gravity brings your back down., 2. Na zdjęciu do filiżanki wlewana jest z dzbanka kawa. When you tilt a water jug, liquid flows to the glass under the influence of gravitational forces., 3. Na zdjęciu schodząca sprężyna. A slinky “comes down” the stairs using gravitational forces.
Ilustracja interaktywna - trzy fotografie. 1. Na zdjęciu dziewczynka skacze na trampolinie. Jump on the trampoline while bending your knees and waving your hands and gravity brings your back down., 2. Na zdjęciu do filiżanki wlewana jest z dzbanka kawa. When you tilt a water jug, liquid flows to the glass under the influence of gravitational forces., 3. Na zdjęciu schodząca sprężyna. A slinky “comes down” the stairs using gravitational forces.
Gravity in everyday life
Source: Marcin Wichary, GroMar Sp. z o.o., licencja: CC BY-SA 3.0.
Mass and weight
Imagine preparing someone weighing 80 kg on Earth for the flight to the Moon. When the rocket enters space and engines are shut down, despite the effects of gravitational force the astronaut will be in a zero gravityzero gravityzero gravity. They no longer weigh anything despite their mass remaining the same. After landing on the Moon, if that person was to weight themselves, the scale would show a value six times lower than on Earth, despite their mass remaining the same. That’s because the gravitational force of the Moon is six times weaker than the Earth’s gravity.
Body mass constantly remains the same, but it’s weightweightweight changes. In certain conditions, the body may even weigh nothing despite having the same exact mass the entire time. Zero gravity also exists on spacecraft floating in Earth orbit at constant speed and with engines shut down.
R1bYDXN9WzIj4
Fotografia wykonana z góry, ukazuje astronautę w stanie nieważkości w niewielkim pomieszczeniu na stacji kosmicznej. Astronauta widoczny ze swojego lewego boku manipuluje przy sprzęcie. Astronauta usytuowany jest na zdjęciu poziomo. Na ścianach pomieszczania przytwierdzone różne sprzęty oraz kable. Poniżej astronauty widoczne przejście do następnego pomieszczenia.
Zero gravity. At the International Space Station (ISS), both people and all objects are in a state of weightlessness
Fotografia prezentuje pierwszego człowieka na Księżycu. Na pierwszym planie widoczny kosmonauta w białym kombinezonie stojący na powierzchni Księżyca, po jego prawej stronie powiewa flaga amerykańska. Na lewo od kosmonauty widoczny pojazd, w tle czarne niebo.
Man on the Moon. The weight of all objects on the Moon is about six times smaller than the same objects on Earth. For this reason, the astronauts had to move very carefully there.
Source: Charlie Duke, NASA.
Important!
Long‑term exposure to zero gravity is hazardous to human health. Muscles gradually atrophy and bones become weaker and brittle. Even intensive physical training only slows down these dangerous processes. Several years of exposure to zero gravity would make return to Earth impossible.
RbWDojpZllZTU
Exercise 1
Complete the sentences by inserting appropriate words. Thanks to gravity, a thrown object will always tu uzupełnij 1. grows, 2. is increased, 3. on objects with a high mass, 4. decreases, 5. floats in the air, 6. flies upward, 7. the less it weights, 8. on objects made from specific materials, 9. on metal objects, 10. reduces its rate of descent, 11. on all objects, 12. the greater the mass, 13. remains the same, 14. the larger its surface, 15. the lowers its mass, 16. is reduced, 17. fall down. Gravity acts equally tu uzupełnij 1. grows, 2. is increased, 3. on objects with a high mass, 4. decreases, 5. floats in the air, 6. flies upward, 7. the less it weights, 8. on objects made from specific materials, 9. on metal objects, 10. reduces its rate of descent, 11. on all objects, 12. the greater the mass, 13. remains the same, 14. the larger its surface, 15. the lowers its mass, 16. is reduced, 17. fall down. The gravitational force is the greater, tu uzupełnij 1. grows, 2. is increased, 3. on objects with a high mass, 4. decreases, 5. floats in the air, 6. flies upward, 7. the less it weights, 8. on objects made from specific materials, 9. on metal objects, 10. reduces its rate of descent, 11. on all objects, 12. the greater the mass, 13. remains the same, 14. the larger its surface, 15. the lowers its mass, 16. is reduced, 17. fall down of the body. If gravity acting on an object is lower, its weight tu uzupełnij 1. grows, 2. is increased, 3. on objects with a high mass, 4. decreases, 5. floats in the air, 6. flies upward, 7. the less it weights, 8. on objects made from specific materials, 9. on metal objects, 10. reduces its rate of descent, 11. on all objects, 12. the greater the mass, 13. remains the same, 14. the larger its surface, 15. the lowers its mass, 16. is reduced, 17. fall down. In such circumstances, its mass tu uzupełnij 1. grows, 2. is increased, 3. on objects with a high mass, 4. decreases, 5. floats in the air, 6. flies upward, 7. the less it weights, 8. on objects made from specific materials, 9. on metal objects, 10. reduces its rate of descent, 11. on all objects, 12. the greater the mass, 13. remains the same, 14. the larger its surface, 15. the lowers its mass, 16. is reduced, 17. fall down.
Complete the sentences by inserting appropriate words. Thanks to gravity, a thrown object will always tu uzupełnij 1. grows, 2. is increased, 3. on objects with a high mass, 4. decreases, 5. floats in the air, 6. flies upward, 7. the less it weights, 8. on objects made from specific materials, 9. on metal objects, 10. reduces its rate of descent, 11. on all objects, 12. the greater the mass, 13. remains the same, 14. the larger its surface, 15. the lowers its mass, 16. is reduced, 17. fall down. Gravity acts equally tu uzupełnij 1. grows, 2. is increased, 3. on objects with a high mass, 4. decreases, 5. floats in the air, 6. flies upward, 7. the less it weights, 8. on objects made from specific materials, 9. on metal objects, 10. reduces its rate of descent, 11. on all objects, 12. the greater the mass, 13. remains the same, 14. the larger its surface, 15. the lowers its mass, 16. is reduced, 17. fall down. The gravitational force is the greater, tu uzupełnij 1. grows, 2. is increased, 3. on objects with a high mass, 4. decreases, 5. floats in the air, 6. flies upward, 7. the less it weights, 8. on objects made from specific materials, 9. on metal objects, 10. reduces its rate of descent, 11. on all objects, 12. the greater the mass, 13. remains the same, 14. the larger its surface, 15. the lowers its mass, 16. is reduced, 17. fall down of the body. If gravity acting on an object is lower, its weight tu uzupełnij 1. grows, 2. is increased, 3. on objects with a high mass, 4. decreases, 5. floats in the air, 6. flies upward, 7. the less it weights, 8. on objects made from specific materials, 9. on metal objects, 10. reduces its rate of descent, 11. on all objects, 12. the greater the mass, 13. remains the same, 14. the larger its surface, 15. the lowers its mass, 16. is reduced, 17. fall down. In such circumstances, its mass tu uzupełnij 1. grows, 2. is increased, 3. on objects with a high mass, 4. decreases, 5. floats in the air, 6. flies upward, 7. the less it weights, 8. on objects made from specific materials, 9. on metal objects, 10. reduces its rate of descent, 11. on all objects, 12. the greater the mass, 13. remains the same, 14. the larger its surface, 15. the lowers its mass, 16. is reduced, 17. fall down.
Complete the sentences by inserting appropriate words.
decreases, remains the same, reduces its rate of descent, flies upward, grows, the greater the mass, is increased, on metal objects, is reduced, fall down, the less it weights, the lowers its mass, on all objects, floats in the air, on objects made from specific materials, on objects with a high mass, the larger its surface
Thanks to gravity, a thrown object will always ............................................................................... Gravity acts equally ............................................................................... The gravitational force is the greater, .............................................................................. of the body. If gravity acting on an object is lower, its weight ............................................................................... In such circumstances, its mass ...............................................................................
R11Jx5boM2cba
Exercise 2
Choose the correct answer that describes the mass of an object in zero gravity. Możliwe odpowiedzi: 1. In zero gravity, the mass of an object is zero., 2. In zero gravity, the mass of an object is reduced., 3. In zero gravity, the mass of an object disappears., 4. In zero gravity, the mass of an object does not change.
Choose the correct answer that describes the mass of an object in zero gravity. Możliwe odpowiedzi: 1. In zero gravity, the mass of an object is zero., 2. In zero gravity, the mass of an object is reduced., 3. In zero gravity, the mass of an object disappears., 4. In zero gravity, the mass of an object does not change.
Choose the correct answer that describes the mass of an object in zero gravity.
In zero gravity, the mass of an object is zero.
In zero gravity, the mass of an object is reduced.
In zero gravity, the mass of an object disappears.
In zero gravity, the mass of an object does not change.
R1YROBKTAvmbj
Exercise 3
Specify whether the statement is true or false.The mass of an object on a planet other than Earth may change. Możliwe odpowiedzi: True, False. In zero gravity, an object does not have mass. Możliwe odpowiedzi: True, False. The mass of an object changes depending on gravitational forces that apply. Możliwe odpowiedzi: True, False. At the Moon, the same object weights six times less than on Earth. Możliwe odpowiedzi: True, False
Specify whether the statement is true or false.The mass of an object on a planet other than Earth may change. Możliwe odpowiedzi: True, False. In zero gravity, an object does not have mass. Możliwe odpowiedzi: True, False. The mass of an object changes depending on gravitational forces that apply. Możliwe odpowiedzi: True, False. At the Moon, the same object weights six times less than on Earth. Możliwe odpowiedzi: True, False
Specify whether the statement is true or false.
True
False
The mass of an object on a planet other than Earth may change.
□
□
In zero gravity, an object does not have mass.
□
□
The mass of an object changes depending on gravitational forces that apply.
□
□
At the Moon, the same object weights six times less than on Earth.
□
□
RD5ILFrGM5yJD
Exercise 4
Match appropriate statements to the following terms. Mass Możliwe odpowiedzi: 1. is reduced six-fold on the Moon, 2. varies depending on the gravitational force, 3. can equal 0 under certain conditions, 4. does not vary depending on the gravitational force, 5. remains unchanged on the Moon Weight Możliwe odpowiedzi: 1. is reduced six-fold on the Moon, 2. varies depending on the gravitational force, 3. can equal 0 under certain conditions, 4. does not vary depending on the gravitational force, 5. remains unchanged on the Moon
Match appropriate statements to the following terms. Mass Możliwe odpowiedzi: 1. is reduced six-fold on the Moon, 2. varies depending on the gravitational force, 3. can equal 0 under certain conditions, 4. does not vary depending on the gravitational force, 5. remains unchanged on the Moon Weight Możliwe odpowiedzi: 1. is reduced six-fold on the Moon, 2. varies depending on the gravitational force, 3. can equal 0 under certain conditions, 4. does not vary depending on the gravitational force, 5. remains unchanged on the Moon
Match appropriate statements to the following terms
remains unchanged on the Moon, can equal 0 under certain conditions, is reduced six-fold on the Moon, varies depending on the gravitational force, does not vary depending on the gravitational force
Mass
Weight
Summary
The force with which one body attracts another is called the gravitational force.
All objects on Earth are affected by gravitational force.
Each object has a mass that never changes and does not depend on gravity.
The weight of a body depends on gravity rather than mass.
