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The first equation shows that, after one second, an object will have fallen a distance of 1/2 × 9.8 × 1 2 = 4.9 m. After two seconds it will have fallen 1/2 × 9.8 × 2 2 = 19.6 m; and so on. On the other hand, the penultimate equation becomes grossly inaccurate at great distances.
The preliminary reference Earth model (PREM) plots the average of Earth's properties by depth. [1] It includes a table of Earth properties, including elastic properties, attenuation, density, pressure, and gravity. PREM has been widely used as the basis for seismic tomography and related global geophysical models. [2]
The gravity g′ at depth d is given by g′ = g(1 − d/R) where g is acceleration due to gravity on the surface of the Earth, d is depth and R is the radius of the Earth. If the density decreased linearly with increasing radius from a density ρ 0 at the center to ρ 1 at the surface, then ρ ( r ) = ρ 0 − ( ρ 0 − ρ 1 ) r / R , and the ...
A relatively simple version [1] of the vertical fluid pressure variation is simply that the pressure difference between two elevations is the product of elevation change, gravity, and density. The equation is as follows: =, where P is pressure, ρ is density, g is acceleration of gravity, and; h is height.
All bodies accelerate in vacuum at the same rate, regardless of the masses or compositions of the bodies; [1] the measurement and analysis of these rates is known as gravimetry. At a fixed point on the surface, the magnitude of Earth's gravity results from combined effect of gravitation and the centrifugal force from Earth's rotation .
Here η is the total fluid column height (instantaneous fluid depth as a function of x, y and t), and the 2D vector (u,v) is the fluid's horizontal flow velocity, averaged across the vertical column. Further g is acceleration due to gravity and ρ is the fluid density. The first equation is derived from mass conservation, the second two from ...
The part between square brackets is the slowly varying amplitude of the group, with group wave number 1 / 2 ( k 1 − k 2 ) and group angular frequency 1 / 2 ( ω 1 − ω 2 ). As a result, the group velocity is, for the limit k 1 → k 2 : [10] [11]
Peak ground acceleration can be expressed in fractions of g (the standard acceleration due to Earth's gravity, equivalent to g-force) as either a decimal or percentage; in m/s 2 (1 g = 9.81 m/s 2); [7] or in multiples of Gal, where 1 Gal is equal to 0.01 m/s 2 (1 g = 981 Gal).