Geologic Time Is Divided Into Units Based Upon Types Of ___

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While Examining Layers Of Rock, A Geologist States, “The Sandstone Is Older Than The Limestone.” What Has The Geologist Determined?

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why do p waves move faster

P-waves move faster because of its ability to penetrate both solid and liquid matter.  They have both bulk and rigidity modulus therefore can compress both solid and liquid matter.

what are two characteristics of p waves

 They are the fastest and can pass through both solid and liquid matters,  the p-wave is a compressional wave with bulk and rigidity modulus , this is why it can pass through solid earth and water bodies.

what are two characteristics of s-waves

 They change the shape of object they pass through them, and can penetrate only solid matter, it has only  bulk modulus , it can only compress object but cannot change their shapes , this is why it has no effect on liquid medium because liquid has no definite shape.

why does s-waves move slower than p-waves

S-wave are slower than p-waves because they do not have rigidity modulus like p-waves, therefore their velocity solely depends on the rigidity modulus which as no effects on liquid( liquids are shapeless).this disable s-waves from propagating through the liquid part of the earth and subsequently reduces its speed.

Comparing Polar Radius vs Equatorial Radius of the Earth

Polar radius vs equatorial radius

The earth is an oblate ellipsoid or spheroid with some bulging at the equator and a flattening at the poles.

 Based on reference ellipsoid accepted by geodesists and geophysicists in 1980, the earth has an equatorial radius of 6378.136km  and a polar radius of 6356.751km.

 But judging from a radius of an equivalent sphere r which is 6371.00km, compared to best fitting sphere the spheroid is flattened by about 14.2km at each pole and the equator  bulges by about 7.1km.

 The polar flattening is defined as the ratio of f=a-c/c,

Where a is equatorial radius and c is polar radius.

 The cause of the polar of the polar flattening is deforming effect of the centrifugal acceleration. This maximum at the equator  where the gravitational acceleration is smallest.