Plate tectonics is a theory about the structure of the earth's crust. In plate tectonics, the continents are viewed as a part of a system of rigid lithospheric plates which move slowly over the underlying mantle of the Earth. The model for plate tectonics builds on the concept of continental drift, which is an idea developed during the first decades of the 20th century. In continental drift theory, all the world's continents were once joined into a land mass that geologists have called Pangea during the late Paleozoic and early Mesozoic eras. It began to break up about 175 million years ago. In the beginning in the late Triassic, the continents began to break up with Laurasia comprising with what is North America and Eurasia and Gondwanaland which was South America and Africa, India, Arabia, Antarctica, and Australia. The shift in plates and their movement create mountain ranges and continents form and move to different latitudes that change the climate as these land masses moved.

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3 years ago

Define G in terms of the gravitational force between two masses .Write its value and SI unit

Ivahew [28]

Definition. According to Newton's law of universal gravitation, the attractive force (F) between two point-like bodies is directly proportional to the product of their masses (m1 andm2), and inversely proportional to the square of the distance, r, (inverse-square law) between them: ... κ = 8πc4G ≈ 2.071×10−43 s2⋅m−1⋅kg−1.

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3 years ago