Further, the corpuscular radiation, i.e., the solar-wind protons, must sputter away the surface atoms of the dust and cause a slow diminution in size, with a resultant increase in both the Poynting-Robertson effect and the ratio of the repulsive force to the gravitational force.

The gravitational force is unchanged at

These forces arise from the presence of the body in force fields, e. g. gravitational field ( gravitational forces ) or electromagnetic field ( electromagnetic forces ), or from inertial forces when bodies are in motion.

In the case of gravitational forces, the intensity of the force depends on, or is proportional to, the mass density of the material, and it is specified in terms of force per unit mass () or per unit volume ().

The oblate spheroid shape reflects, following Clairaut's theorem, the balance between containment by gravitational attraction and dispersal by centrifugal force.

The gravitational force acts on each object toward the other, which is toward the center of mass of the two objects ; for circular orbits, this center of gravity is the center of the circular orbits.

For non-circular orbits or trajectories, only the component of gravitational force directed orthogonal to the path ( toward the center of the osculating circle ) is termed centripetal ; the remaining component acts to speed up or slow down the satellite in its orbit.

There are two forces ; one is the force of gravity vertically downward through the center of mass of the ball mg where m is the mass of the ball and g is the gravitational acceleration ; the second is the upward normal force exerted by the road perpendicular to the road surface ma < sub > n </ sub >.

The other fundamental forces are: the strong nuclear force, which binds quarks to form nucleons, and binds nucleons to form nuclei, the weak nuclear force, which causes certain forms of radioactive decay, and the gravitational force.

In comparison with the much weaker gravitational force, the electromagnetic force pushing two electrons apart is 10 < sup > 42 </ sup > times that of the gravitational attraction pulling them together.

Once this electromagnetic field has been produced from a given charge distribution, other charged objects in this field will experience a force ( in a similar way that planets experience a force in the gravitational field of the Sun ).

However, some emulsions would never coalesce under normal gravitational force, but will under higher g forces.

There may be hypothetical elementary particles not described by the Standard Model, such as the graviton, the particle that would carry the gravitational force, and sparticles, supersymmetric partners of the ordinary particles.

A simplified version of this is embodied in Einstein's elevator experiment, illustrated in the figure on the right: for an observer in a small enclosed room, it is impossible to decide, by mapping the trajectory of bodies such as a dropped ball, whether the room is at rest in a gravitational field, or in free space aboard an accelerating rocket generating a force equal to gravity.

Given the universality of free fall, there is no observable distinction between inertial motion and motion under the influence of the gravitational force.

The water surface is flat at first, and clearly a surface of equal potential energy because all points on the surface are at the same height in the gravitational field acting upon the water.

Weight is the gravitational force acting on a given body — which differs depending on the gravitational pull of the opposing body ( e. g. a person's weight on Earth vs on the Moon ) — while mass is an intrinsic property of that body that never changes.

Thus, for instance, forces that act on particles are frequently derived from fields ( electromagnetic or gravitational ), and particles generate fields by acting as sources.

This is a natural consequence of their low temperatures and high densities, since the gravitational force acting to collapse the cloud may exceed the internal pressures that are acting " outward " to prevent a collapse.

Since the floating hydrometer is in static equilibrium, the downward gravitational force acting upon it must exactly balance the upward buoyancy force.

As the orbit has been assumed circular, the total gravitational force and centrifugal force acting on the main body cancel.

* The force acting on a certain object due to gravity is directly proportional to the object's mass ; the constant of proportionality between the mass and the force is known as gravitational acceleration.

When it is necessary to consider a gravitational torque, it is easier to represent gravity as a force acting at the center of mass, plus an orientation-dependent couple.

A system consists of a well-sealed object of mass m and volume V which is fully submerged in a uniform fluid body of density ρ < sub > f </ sub > and in an environment of a uniform gravitational field g. Under the forces of buoyancy and gravity alone, the " dynamic buoyancy force " B acting on the object and its upward acceleration a are given by:

Even though electrostatically induced forces seem to be rather weak, the electrostatic force between e. g. an electron and a proton, that together make up a hydrogen atom, is about 40 orders of magnitude stronger than the gravitational force acting between them.

An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon this mean flow, such as breaking waves, wind, Coriolis effect, cabbeling, temperature and salinity differences and tides caused by the gravitational pull of the Moon and the Sun.

The gravitational mass is the quantity that determines the strength of the gravitational field generated by an object, as well as the gravitational force acting on the object when it is immersed in a gravitational field produced by other bodies.

According to Newton's law of gravitation, the gravitational force,, acting on a mass, due to a mass which is a distance away, obeys the equation

Thus, perpendicular components of forces acting on massless particles simply change their direction of motion, the angle change in radians being GM / rc < sup > 2 </ sup > with gravitational lensing, a result predicted by general relativity.

When the gravitational force acting on a slope exceeds its resisting force, slope failure ( mass wasting ) occurs.

# Elevation head is due to the fluid's weight, the gravitational force acting on a column of fluid.

saying that the net gravitational forces acting on the point mass from the mass elements of the shell, outside the measurement point, cancel out.

Their lungs improved and their skeletons became heavier and stronger, better able to cope with the increased gravitational effect of life on land.

With the definitions used before 2012, the astronomical unit was dependent on the heliocentric gravitational constant, that is the product of the gravitational constant G and the solar mass M < sub >☉</ sub >.

) During the collapse, neutrons are formed by the capture of electrons by protons in the process of electron capture, leading to the emission of neutrinos .< sup >, pp. 1046 – 1047 .</ sup > The decrease in gravitational potential energy of the collapsing core releases a large amount of energy which is on the order of 10 < sup > 46 </ sup > joules ( 100 foes ).

* Computer models of gravitational collapse have shown that naked singularities can arise, but these models rely on very special circumstances ( such as spherical symmetry ).

Instead, its existence and properties are inferred from its gravitational effects on visible matter, radiation, and the large scale structure of the universe.

Dark matter's existence is inferred from gravitational effects on visible matter and gravitational lensing of background radiation, and was originally hypothesized to account for discrepancies between calculations of the mass of galaxies, clusters of galaxies and the entire universe made through dynamical and general relativistic means, and calculations based on the mass of the visible " luminous " matter these objects contain: stars and the gas and dust of the interstellar and intergalactic medium.

Gravitational lensing observations of galaxy clusters allow direct estimates of the gravitational mass based on its effect on light from background galaxies, since large collections of matter ( dark or otherwise ) will gravitationally deflect light.

The orientation of the Earth's axis and equator are not fixed in space, but rotate about the poles of the ecliptic with a period of about 26, 000 years, a process known as lunisolar precession, as it is due mostly to the gravitational effect of the Moon and Sun on the Earth's equatorial bulge.

Technological advances, most notably in high-resolution spectroscopy, led to the rapid detection of many new exoplanets: astronomers could detect exoplanets indirectly by measuring their gravitational influence on the motion of their parent stars.

In 1921, his third year at the university, he published his first scientific works in the Italian journal Nuovo Cimento: the first was titled: On the dynamics of a rigid system of electrical charges in translational motion ; the second: On the electrostatics of a uniform gravitational field of electromagnetic charges and on the weight of electromagnetic charges.

The changing rates of clocks allowed Einstein to conclude that light waves change frequency as they move, and the frequency / energy relationship for photons allowed him to see that this was best interpreted as the effect of the gravitational field on the mass – energy of the photon.

This new class of preferred motions, too, defines a geometry of space and time — in mathematical terms, it is the geodesic motion associated with a specific connection which depends on the gradient of the gravitational potential.

For weak gravitational fields and slow speed relative to the speed of light, the theory's predictions converge on those of Newton's law of universal gravitation.

In the parameterized post-Newtonian formalism ( PPN ), measurements of both the deflection of light and the gravitational time delay determine a parameter called γ, which encodes the influence of gravity on the geometry of space.

Such linearized gravitational waves are sufficiently accurate to describe the exceedingly weak waves that are expected to arrive here on Earth from far-off cosmic events, which typically result in relative distances increasing and decreasing by or less.

In 1750 the English astronomer Thomas Wright, in his An original theory or new hypothesis of the Universe, speculated ( correctly ) that the galaxy might be a rotating body of a huge number of stars held together by gravitational forces, akin to the solar system but on a much larger scale.