Gravity of Earth

The gravity of Earth, denoted by g, is the net acceleration that is imparted to objects due to the combined effect of gravitation (from mass distribution within Earth) and the centrifugal force (from the Earth's rotation). It is a vector quantity, whose direction coincides with a plumb bob and strength or magnitude is given by the norm g=|\mathit{\mathbf{g}}|. In SI units this acceleration is expressed in metres per second squared (in symbols, m/s2 or m·s−2) or equivalently in newtons per kilogram (N/kg or N·kg−1). Near Earth's surface, the acceleration due to gravity, accurate to 2 significant figures, is . This means that, ignoring the effects of air resistance, the speed of an object falling freely will increase by about per second every second. This quantity is sometimes referred to informally as little g (in contrast, the gravitational constant G is referred to as big G). The precise stren

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Publications associées (22)

Publications associées

Chargement

Personnes associées (2)

Personnes associées

Chargement

Unités associées (2)

Unités associées

Chargement

Concepts associés (44)

Concepts associés

Chargement

Cours associés (41)

Cours associés

Chargement

Séances de cours associées (75)

Séances de cours associées

Chargement

PHYS-427: Relativity and cosmology I

Introduce the students to general relativity and its classical tests.

PHYS-101(en): General physics : mechanics (English)

Students will learn the principles of mechanics to enable a better understanding of physical phenomena, such as the kinematics and dyamics of point masses and solid bodies. Students will acquire the capacity to quantitatively analyze these effects with the appropriate theoretical tools.

MATH-106(a): Analysis II

Étudier les concepts fondamentaux d'analyse, et le calcul différentiel et intégral des fonctions réelles de plusieurs variables.

Missing water from the Qiangtang Basin on the Tibetan Plateau

David Andrew Barry, Jiaqi Chen, Tao Wang

The Qiangtang Basin is a large endorheic basin in the inner part of the Tibetan Plateau and has been thought to be a dry region in contrast with its wet surrounding outer region that feeds all the major Asian rivers. Combining surface hydrological data with modelling and satellite data between 2002 and 2016, our study reveals that an enormous amount of water, approximately 54 ± 4 cubic kilometers, is unaccounted for annually in the Qiangtang Basin. The amount of missing water is comparable to the total annual discharge of the Yellow River. Data from the Gravity Recovery and Climate Experiment (GRACE) show little increase of local terrestrial water storage. Thus, the missing water must have flowed out of the basin through underground passages. Interpreting this result in the context of recent seismic and geological studies of Tibet, we suggest that a significant amount of meteoric water in the Qiangtang Basin leaks out by way of groundwater flow through deep normal faults and tensional fractures along the nearly N-S rift valleys that are oriented sub-normal to and cross the surficial hydrological divide on the southern margin of the basin. Cross-basin groundwater outflow of such a magnitude defies the traditional view of basin-scale water cycle and leads to a very different picture from the previous hydrological view of the Qiangtang Basin. The finding calls for major rethinking of the regional water balance.

2021

Chargement

Coupling metric-affine gravity to a Higgs-like scalar field

Sebastian Zell

General relativity (GR) exists in different formulations. They are equivalent in pure gravity but generically lead to distinct predictions once matter is included. After a brief overview of various versions of GR, we focus on metric-affine gravity, which avoids any assumption about the vanishing of curvature, torsion, or nonmetricity. We use it to construct an action of a scalar field coupled nonminimally to gravity. It encompasses as special cases numerous previously studied models. Eliminating nonpropagating degrees of freedom, we derive an equivalent theory in the metric formulation of GR. Finally, we give a brief outlook of implications for Higgs inflation.

AMER PHYSICAL SOC2022

Chargement

Quasilocalized gravity without asymptotic flatness

Katarzyna Zuleta Estrugo

We present a toy model of a generic five-dimensional warped geometry in which the 4D graviton is not fully localized on the brane. Studying the tensor sector of metric perturbation around this background, we find that its contribution to the effective gravitational potential is of 4D type (1/r) at the intermediate scales and that at the large scales it becomes 1/r 1+α, 0 < α ≤ 1 being a function of the parameters of the model (α = 1 corresponds to the asymptotically flat geometry). Large-distance behavior of the potential is therefore not necessarily five-dimensional. Our analysis applies also to the case of quasilocalized massless particles other than graviton. © 2004 The American Physical Society.

2004

Chargement

Terre

La Terre est la troisième planète par ordre d'éloignement au Soleil et la cinquième plus grande du Système solaire aussi bien par la masse que par le diamètre. Par ailleurs, elle est le seul objet cé

Géoïde

Un géoïde est une surface équipotentielle de référence du champ de pesanteur terrestre. Un géoïde est déterminé à terre par nivellement géométrique en utilisant aussi les mesures de gravimétrie ; les

Mètre

Le mètre, de symbole m (sans point abréviatif), est l'unité de longueur du Système international (SI). C'est l'une de ses sept unités de base, à partir desquelles sont construites les unités dérivées