Structure of the Earth easily than does the upper mantle (chemical changes within the mantle may also be important). The viscosity of the mantle ranges between 10 and 10 Pa·s, depending on depth. In comparison, the viscosity of water is approximately 10 Pa·s and that of pitch is 10 Pa·s. The source of heat that drives plate tectonics is the primordial heat left over from the planet’s formation as well as the radioactive decay of uranium, thorium, and potassium in Earth’s crust and mantle. The average density of Earth is . Because the average density of surface material is only around , we must
What Do You See? What Do You See? "What Do You See?" (就在这里 in Mandarin) is a song by Singaporean band Electrico. It was commissioned as the official theme song for the 2009 National Day Parade. The song is one of the few National Day Parade theme songs that does not mention the word ""Singapore"" in its lyrics. Its lyrics were cited by Prime Minister Lee Hsien Loong in his 2018 National Day Message. Directed by Bertrand Lee, the music video opens with a bokeh and later sharpens to reveal band member David Tan. The camera then traces him around the downtown core of