The information presented below were all obtained from various internet sources (all of which are listed below) and this post is a compilation and a summary, in simple words for ease of understanding of the readers, of the whole process taken into consideration for the research.) Nothing has been directly pasted from a single source.
A quantity that can be used to describe the overall state of a physical system is said to be Angular Momentum. . Angular momentum is always conserved in a system where there is no net external moment of force.
For a rigid body rotating around an axis of symmetry (e.g. the fins of a ceiling fan, or the earth), the angular momentum can be expressed as the product of the body's moment of inertia (a measure of an object's resistance to changes in its rotation rate) and its angular velocity ω:
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The earth has its own Angular Momentum which is conserved. This means, that if either part of its product, i.e. the moment of inertia or the angular velocity rises, the other value of the other will fall and vice versa, in order to maintain a constant value for the Angular Momentum of the earth.
The earth can be considered a Solid Sphere, and the moment of inertia of a Solid Sphere is given by the formula :
Photo:This photo has not been acquired from any online source and is created using Microsoft Word and Micro Soft Paint by the group.
So we can say that the Earth’s Angular Momentum can be calculated by the following formula:
Photo:This photo has not been acquired from any online source and is created using Microsoft Word and Micro Soft Paint by the group.
The earthquake in Japan caused a change,a slight decrease, in the Earth’s radius as a result of the subduction of the Tectonic plates. This decrease in the radius however is very very very small in comparison to the earth’s radius before the change. This will cause the value of R in our formula will reduce. The total mass of earth still remains constant ensuring that the M value remains unchanged. Therefore, in order to keep the value of L constant (conservation of Angular Momentum), the value of the angular velocity ω will rise (by a very small amount), thus slightly speeding up the velocity at which the earth rotates and in turns shortening the 24 hour day in earth by a few micro seconds, 1.8 micro seconds to be more specific.
Source : http://en.wikipedia.org/wiki/Angular_momentum,
http://en.wikipedia.org/wiki/Moment_of_inertia.
http://hyperphysics.phy-astr.gsu.edu/hbase/isph.html
http://en.wikipedia.org/wiki/Moment_of_inertia.
http://hyperphysics.phy-astr.gsu.edu/hbase/isph.html
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