How solar storms play havoc with our lives
Despite the 150 million kilometers that separate it from the Earth, the sun does more than just light our way: it also impacts our electricity networks, and even our transport.
Despite the 150 million kilometers that separate it from the Earth, the sun does more than just light our way: it also impacts our electricity networks, and even our transport.
Planetary Sciences
8 hours ago
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Using radar, a Nasa spacecraft, Lunar Reconnaissance Orbiter (LRO), has confirmed the existence of caves beneath the lunar surface. Here's why such geological features will be key for establishing a base on the moon, and ...
Planetary Sciences
Jul 25, 2024
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A team of geoscientists affiliated with several institutions in the U.S. and Switzerland has more precisely dated an enormous "magmatic event" that occurred on the moon several billion years ago.
Brachiopods were evolving in new directions but this did not become an evolutionary success in terms of the numbers of species, researchers at the University of Bristol, the Open University, and the China University of Geosciences ...
Evolution
Jul 25, 2024
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Using the TÜBİTAK National Observatory (TUG) and NASA's Transiting Exoplanet Survey Satellite (TESS), astronomers have investigated a short-period contact binary known as CC Com. As a result, they detected two additional ...
For years, scientists believed that changes in the Earth's interior, such as volcanic eruptions and tectonic plate collisions, primarily affected the surface environment. Events such as the mass extinction around 66 million ...
Earth Sciences
Jul 23, 2024
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Space storms could soon be forecast with greater accuracy than ever before thanks to a big leap forward in our understanding of exactly when a violent solar eruption may hit Earth.
Astronomy
Jul 19, 2024
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The first rumblings of the sun's next 11-year solar cycle have been detected in sound waves inside our home star—even though it is only halfway through its current one.
Astronomy
Jul 18, 2024
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Dry fruits are divided into dehiscent and indehiscent types based on whether the pericarp splits open after reaching maturity. As a maternal tissue, the pericarp may provide seeds with different germination strategies.
Plants & Animals
Jul 18, 2024
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Using the Keck II telescope, astronomers have detected an object that may be a brown dwarf or a low-mass star, exhibiting a very high radial velocity. The object, designated CWISE J124909.08+362116.0 is located some 400 light ...
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity. In physics, mass (from Ancient Greek: μᾶζα) commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:
Mass must be distinguished from matter in physics, because matter is a poorly-defined concept, and although all types of agreed-upon matter exhibit mass, it is also the case that many types of energy which are not matter—such as potential energy, kinetic energy, and trapped electromagnetic radiation (photons)—also exhibit mass. Thus, all matter has the property of mass, but not all mass is associated with identifiable matter.
In everyday usage, "mass" is often used interchangeably with weight, and the units of weight are often taken to be kilograms (for instance, a person may state that their weight is 75kg). In scientific use, however, the two terms refer to different, yet related, properties of matter. Weight can be zero if no gravitational force is acting but mass can never be zero.
The inertial mass of an object determines its acceleration in the presence of an applied force. According to Newton's second law of motion, if a body of fixed mass M is subjected to a force F, its acceleration α is given by F/M.
A body's mass also determines the degree to which it generates or is affected by a gravitational field. If a first body of mass MA is placed at a distance r from a second body of mass MB, each body experiences an attractive force F whose magnitude is
where G is the universal constant of gravitation, equal to 6.67×10−11 N m2kg-2. This is sometimes referred to as gravitational mass (when a distinction is necessary, M is used to denote the active gravitational mass and m the passive gravitational mass). Repeated experiments since the 17th century have demonstrated that inertial and gravitational mass are equivalent; this is entailed in the equivalence principle of general relativity.
Special relativity shows that rest mass (or invariant mass) and rest energy are essentially equivalent, via the well-known relationship (E=mc2). This same equation also connects relativistic mass and "relativistic energy" (total system energy). These are concepts that are related to their "rest" counterparts, but they do not have the same value, in systems where there is a net momentum. In order to deduce any of these four quantities from any of the others, in any system which has a net momentum, an equation that takes momentum into account is needed.
Mass (so long as the type and definition of mass is agreed upon) is a conserved quantity over time. From the viewpoint of any single unaccelerated observer, mass can neither be created or destroyed, and special relativity does not change this understanding (though different observers may not agree on how much mass is present, all agree that the amount does not change over time). However, relativity adds the fact that all types of energy have an associated mass, and this mass is added to systems when energy is added, and the associated mass is subtracted from systems when the energy leaves. In such cases, the energy leaving or entering the system carries the added or missing mass with it, since this energy itself has mass. Thus, mass remains conserved when the location of all mass is taken into account.
On the surface of the Earth, the weight W of an object is related to its mass m by
where g is the Earth's gravitational field strength, equal to about 9.81 m s−2. An object's weight depends on its environment, while its mass does not: an object with a mass of 50 kilograms weighs 491 newtons on the surface of the Earth; on the surface of the Moon, the same object still has a mass of 50 kilograms but weighs only 81.5 newtons.
This text uses material from Wikipedia, licensed under CC BY-SA