Technology & Engineering
Gravitational Attraction
Gravitational attraction is the force of attraction between two objects with mass. According to Newton's law of universal gravitation, the force of gravitational attraction is directly proportional to the product of the masses of the objects and inversely proportional to the square of the distance between their centers. This fundamental force governs the motion of celestial bodies and is crucial in fields such as astronomy and physics.
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4 Key excerpts on "Gravitational Attraction"
- Thais Russomano, Gustavo Dalmarco, Felipe Prehn Falcao(Authors)
- 2022(Publication Date)
- Springer(Publisher)
Gravitation is also responsible for keeping the Earth and the other planets in their orbits around the sun, the Moon in its orbit around the Earth, the formation of tides, and various other natural phenomena that are commonly observed (Figure 1.1). Gravity, however, is the gravitation related to Earth. It is then the gravitational force that occurs between the Earth and other bodies, the force acting to pull objects toward the Earth. It is expressed as 1G (capital “G,” as opposed to the acceleration g). Bodies with less mass than the Earth will have values lower than 1G (the Moon has 1/6G), and bodies with mass bigger than the Earth will have values higher than 1G (planet Jupiter has 3.5G). C H A P T E R 1 General Concepts in Physics— Definition of Physical Terms 2 EFFECTS OF HYPER- AND MICROGRAVITY ON BIOMEDICAL EXPERIMENTS Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to and is expressed by the symbol m. Acceleration (expressed by the symbol a) is defined as the rate of change of velocity. It is thus a vector quantity with dimension length/time² (SI units m/s²), and the instantaneous accelera- tion of an objection is given by Equation 1.1. By being a vector, it must be described with both a direction and a magnitude. It can have positive and negative values — called acceleration (increasing speed) and deceleration (decreasing speed), respectively, as well as change in direction. a dv dt (1.1) where a is acceleration, v is velocity, t is time, and d is Leibniz’s notation for differentiation. Gravitation is one of the four fundamental interactions in nature, the other three being the electromagnetic force, the weak nuclear force, and the strong nuclear force. Compared to the other three fundamental interactions in nature, gravitation is the weakest one. It, however, acts over great distances and is always present. Gravitation is interpreted differently by classic mechanics, relativity, and quantum physics.
- David Halliday, Robert Resnick, Jearl Walker(Authors)
- 2023(Publication Date)
- Wiley(Publisher)
Moreover, this “stuff” always attracts other “stuff,” never repelling it (or a hard sneeze could put us into orbit). In the past people obviously knew that they were being pulled downward (especially if they tripped and fell over), but they fig- ured that the downward force was unique to Earth and unrelated to the apparent movement of astronomical bodies across the sky. But in 1665, the 23-year-old Isaac Newton recognized that this force is responsible for holding the Moon in its orbit. Indeed he showed that every body in the universe attracts every other body. This tendency of bodies to move toward one another is called gravi- tation, and the “stuff” that is involved is the mass of each body. If the myth were true that a falling apple inspired Newton’s law of gravitation, then the attraction is between the mass of the apple and the mass of Earth. It is appreciable because the mass of Earth is so large, but even then it is only about 0.8 N. The attraction between two people standing near each other on a bus is (thankfully) much less (less than 1 N) and imperceptible. The Gravitational Attraction between extended objects such as two people can be difficult to calculate. Here we shall focus on Newton’s force law between two particles (which have no size). Let the masses be m 1 and m 2 and r be their separation. Then the magnitude of the gravitational force acting on each due to the presence of the other is given by F = G m 1 m 2 _____ r 2 (Newton’s law of gravitation). (13.1.1) G is the gravitational constant: G = 6.67 × 10 −11 N · m 2 /kg 2 = 6.67 × 10 −11 m 3 /kg · s 2 . (13.1.2) In Fig. 13.1.2a, F → is the gravitational force acting on particle 1 (mass m 1 ) due to particle 2 (mass m 2 ). The force is directed toward particle 2 and is said to be an attractive force because particle 1 is attracted toward particle 2.
eBook - ePubFluids, Materials and Microgravity
Numerical Techniques and Insights into Physics
- Marcello Lappa(Author)
- 2004(Publication Date)
- Elsevier Science(Publisher)
CHAPTER 1Space research
1.1 What is microgravity?
Gravitational Attraction is a fundamental property of matter that exists throughout the known universe. The presence of Earth creates a gravitational field that acts to attract objects with a force inversely proportional to the square of the distance between the center of the object and the center of Earth. When the acceleration of an object acted upon only by Earth’s gravity at the Earth’s surface is measured, it is commonly referred to as one-g (1g) or one Earth gravity. This acceleration is approximately 9.8 meters per second squared (m/s2 ). The weight of an object is the gravitational force exerted on it by Earth.While the mass of an object is constant and the weight of an object is constant (ignoring differences in g at different locations on the Earth’s surface), the environment of an object may be changed in such a way that its apparent weight changes.Although gravity is a universal force, there are times, in fact, when it is not desirable to conduct scientific research under its full influence. In these cases, scientists perform their experiments in “microgravity,” a condition in which the effects of gravity are greatly reduced, sometimes described as “weightlessness.” This description brings to mind images of astronauts and objects floating around inside an orbiting spacecraft, seemingly free of Earth’s gravitational field, but these images are misleading. The pull of Earth’s gravity actually extends far into space. To reach a point where the Earth’s gravity is reduced to one-millionth of that on Earth’s surface, one would have to be 6.37 million kilometers away from Earth (almost 17 times farther away than the Moon). Since spacecraft usually orbit only 200–450 km above Earth’s surface, there must be another explanation for the microgravity environment found aboard these vehicles (Rogers et al., 1997
- David Halliday, Jearl Walker, Patrick Keleher, Paul Lasky, John Long, Judith Dawes, Julius Orwa, Ajay Mahato, Peter Huf, Warren Stannard, Amanda Edgar, Liam Lyons, Dipesh Bhattarai(Authors)
- 2020(Publication Date)
- Wiley(Publisher)
Although the gravitational force is still not fully understood, the starting point in our understanding of it lies in the law of gravitation of Isaac Newton. Newton’s law of gravitation Before we get to the equations, let’s just think for a moment about something that we take for granted. We are held to the ground just about right, not so strongly that we have to crawl to get to school (though an occasional exam may leave you crawling home) and not so lightly that we bump our heads on the ceiling when we take a step. It is also just about right so that we are held to the ground but not to each other (that would be awkward in any classroom) or to the objects around us (the phrase ‘catching a bus’ would then take on a new meaning). The attraction obviously depends on how much ‘stuff’ there is in ourselves and other objects: Earth has lots of ‘stuff’ and produces a big attraction, but another person has less ‘stuff’ and produces a smaller (even negligible) attraction. Moreover, this ‘stuff’ always attracts other ‘stuff’, never repelling it (or a hard sneeze could put us into orbit). In the past people obviously knew that they were being pulled downward (especially if they tripped and fell over), but they figured that the downward force was unique to Earth and unrelated to the apparent movement of astronomical bodies across the sky. But in 1665, 23‐year‐old Isaac Newton recognised that this force is responsible for holding the Moon in its orbit. Indeed, he showed that every body in the universe attracts every other body. This tendency of bodies to move towards one another is called gravitation, and the ‘stuff’ that is involved is the mass of each body. If the myth were true that a falling apple inspired Newton to his law of gravitation, then the attraction is between the mass of the apple and the mass of Pdf_Folio:241 CHAPTER 13 Gravitation 241 Earth. It is appreciable because the mass of Earth is so large, but even then it is only about 0.8 N.
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