# Tidal Force

The tidal force is a secondary effect of the force of gravity and is responsible for the tides. It arises because the gravitational force per unit mass exerted on one body by a second body is not constant across its diameter, the side nearest to the second being more attracted by it than the side farther away. Stated differently, the tidal force is a differential force. Consider three things being pulled by the moon: the oceans nearest the moon, the solid earth, and the oceans farthest from the moon. The moon pulls on the solid earth, but it pulls harder on the near oceans, so they approach the moon more causing a high tide; and the moon pulls least of all on the far oceans (on the other side of the planet). This could be expected to cause a low tide but the inertia of the Earth's rotation around the Earth-Moon barycentre causes the second high tide opposite the gravitational one. If we imagine looking at the Earth from space, we see that the whole Earth was pulled, but the near oceans more and the far oceans less; the far oceans stayed behind since they are pulled less (since they are farther away).

In a more general usage in celestial mechanics, the expression 'tidal force' can refer to a situation in which a body or material (for example, tidal water, or the Moon) is mainly under the gravitational influence of a second body (for example, the Earth), but is also perturbed by the gravitational effects of a third body (for example, by the Moon in the case of tidal water, or by the Sun in the case of the Moon). The perturbing force is sometimes in such cases called a tidal force (for example, the perturbing force on the Moon): it is the difference between the force exerted by the third body on the second and the force exerted by the third body on the first.

Read more about Tidal Force:  Explanation, Effects of Tidal Forces, Mathematical Treatment, Relation With Centrifugal Force

### Other articles related to "tidal force, force, forces, tidal":

High Water - Physics - Forces
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Tidal Force - Relation With Centrifugal Force
... If a secondary body orbits a primary body, the forces that could tear the second body apart if its strength and internal gravity are not enough, are the tidal force and the "ce ...
High Water - Tidal Constituents - Principal Lunar Semi-diurnal Constituent
... is the "principal lunar semi-diurnal", also known as the M2 (or M2) tidal constituent ... Its period is about 12 hours and 25.2 minutes, exactly half a tidal lunar day, which is the average time separating one lunar zenith from the next, and thus is the time required for the Earth to rotate once relative to ... so in many places the period of strongest tidal forcing is the above mentioned, about 12 hours and 25 minutes ...
Antigravity - Conventional Effects That Mimic Anti-gravity Effects
... suspends an object against gravity by use of electromagnetic forces ... A tidal force causes objects to move along diverging paths near a massive body (such as a planet or star), producing effects that seem like repulsion or disruptive forces when observed locally ... In Newtonian mechanics, the tidal force is the effect of the larger object's gravitational force being different at the differing locations of the diverging ...
Themed Areas - The Boardwalk At Hersheypark
... with three already standing rides Roller Soaker, Tidal Force and Canyon River Rapids ... Canyon River Rapids and Tidal Force were rezoned from Pioneer Frontier to the Boardwalk, with Tidal Force later being zoned as Midway America ...

### Famous quotes containing the words force and/or tidal:

If writers were too wise, perhaps no books would get written at all. It might be better to ask yourself “Why?” afterwards than before. Anyway, the force from somewhere in Space which commands you to write in the first place, gives you no choice. You take up the pen when you are told, and write what is commanded. There is no agony like bearing an untold story inside you.
Zora Neale Hurston (1891–1960)

And now it is once more the tidal wave
That when it was swept by, leaves summits stained.
Oh, blood will out. It cannot be contained.
Robert Frost (1874–1963)