# Characteristic and Internal Structure of the Earth Flashcards

What shape is the Earth and why is this?

The Earth is an ‘oblate spheroid’. The bulge occurs due to the rotation of the Earth, as the Earth s slightly plastic (deformable).

What is the approximate radius of the Earth?

6378km

About how much does the Earth radius vary due to mountains and oceans?

+/- 20km

What is an equation to approximate the actual radius of the Earth considering the bulge in terms of the latitude?

R(λ) = Req(1-f*sin^2(λ))

where f is the flattening

What is the equation for f, the flattening of the Earth?

f = (Req - Rpol)/Req

What is the approximate radius from pole to pole of the Earth?

Around 22km less than at the equator.

What is latitude? What is its symbol?

Specifies the north-south position of a point on the surface. Runs from 90°N - 90°S, where 0° is the equator. Symbol can either be λ or ϕ

What is longitude? What is its symbol?

Specifies the east-west position of a point on the surface. Relative to defined meridian at Greenwich. Goes from 180°W to 180°E. Symbol can either be λ or ϕ

What is Δ in Geophysics?

Angular distance in radians.

What is the equation for actual distance in terms of angular distance?

X = Req * Δ

where Δ is the angular distance.

What is the Cavendish experiment and what was found?

Torsion balance used to measure gravitational attraction between two large masses and compare this to their weight using Newton’s law.

What is Newton’s law of universal gravitation?

F = GMm/r^2

Who drilled the deepest into the Earth and how far did they go?

Drilled to 12,262 metres before the temperature forced them to stop from 1970-1989.

What is the equation for gravitational acceleration including Req?

geq = GMe/Req

What is the integral equation for the moment of inertia?

I = integral over V of r^2 dm