Land: Tectonic plate movement under the Earth can create landforms by pushing up mountains and hills. Erosion by water and wind can wear down land and create landforms like valleys and canyons. ... Landforms can exist under water in the form of mountain ranges and basins under the sea.
Atmosphere: (4.6 billion years ago)
As Earth cooled, an atmosphere formed mainly from gases spewed from volcanoes. It included hydrogen sulfide, methane, and ten to 200 times as much carbon dioxide as today's atmosphere. After about half a billion years, Earth's surface cooled and solidified enough for water to collect on it.
Ocean: After the Earth's surface had cooled to a temperature below the boiling point of water, rain began to fall—and continued to fall for centuries. As the water drained into the great hollows in the Earth's surface, the primeval ocean came into existence. The forces of gravity prevented the water from leaving the planet.
Because the top layer of a pool will be warmer than the bottom layer, that why filtration is important to cycle the water evenly.
Answer:
a) The force is zero, or the displacement is zero, or the angle is 180 degrees
b) The kinetic energy, speed, and velocity of the particle change.
c) W1 = - W2
Answer:
Explanation:
Given
Speed of Primary wave 
Speed of secondary wave 
difference in timing of two waves are 
Suppose both travel a distance of d km then
Subtract (ii) from (i)
![d[\frac{1}{4.5}-\frac{1}{8}]=77.2](https://tex.z-dn.net/?f=d%5B%5Cfrac%7B1%7D%7B4.5%7D-%5Cfrac%7B1%7D%7B8%7D%5D%3D77.2)
![d[0.0972]=77.2](https://tex.z-dn.net/?f=d%5B0.0972%5D%3D77.2)
Not sure we can open those image files, but I think it would be 6.3*10^0
