Answer:
Much of our understanding of the basic structure and composition of Earth and the other planets in our solar system is not strenuously debated. We can infer a surprising amount of information from the size, mass and moment of inertia of the planets, all of which can be determined from routine astronomical observations. Measurements of surface chemical composition, either by direct sampling (as has been done on Earth, the moon, and Mars) or through spectroscopic observations, can be used to estimate elemental abundances and the degree of chemical differentiation that occurred as the planets condensed from the solar nebula. Remote observations of the gravitational field can be used to understand how a planet's mass is distributed, whereas the strength and shape of the magnetic field provides some constraint on the structure of a metallic core. The specifics of structure and composition, however, are much more debatable. And it is these details that tell us a much more extensive and ultimately more interesting story about the internal dynamics of the planets and their evolution. As a result, trying to determine them is frontier research in almost all fields of earth and planetary science.
Even on Earth, many of these details have to be inferred from remote observations. Because we cannot sample the deep Earth, we must deduce its composition either by looking at the clues hidden in igneous and metamorphic rocks, or by examining proxies for composition and structure such as the three-dimensional variation of the velocity of seismic waves produced by earthquakes and sampled by networks of seismometers on the surface. The late Francis Birch, the eminent Harvard geophysicist, and his colleagues and students worked out the basic methodology that brings these distinct observations together. Birch showed how the stiffness of rocks changes under the extreme conditions of pressure and temperature deep within planets, as well as with chemical composition. Because the speed of seismic waves depends on the stiffness of the medium through which they propagate, it is possible to calculate temperature and composition from maps of seismic velocity. Most current research is based on Birch's work and it has even been extended to the most extreme temperature and pressure conditions of Earth's core. For example, much of our understanding of the large- and small-scale convection patterns driving plate tectonics has come about by using Birch-type proxies for temperature and composition.
Explanation:
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Answer:
The big rip theory
Explanation:
I believe what you are referring to is the big rip theory, in which the universe expands faster than the speed of light Kurzgesagt refers to it as a "horizon" but in reality it's a little more complicated than that. Eventually the expansion of the universe will accelerate far beyond the speed of light creating space between molecules until eventually all matter is fleeting and the entire universe is an endlessly vast cosmic void with not but the occasion molecule left from a time when things weren't so lonely.
<span>The answer is -0.8 m/s. We know acceleration is the average of final minus initial velocity over time (a = (vf-v0)/t). We also know that Force is equal to Mass times Acceleration (F = ma). Using our force equation, we know that the acceleration we get is negative 8.8 (-8.8). The force is acting in the opposite direction of the rugby player, hence the negative sign. From there, plug in that number for a in the velocity equation, and solve for vf, as v0 and t are known. We get 0.8 m/s in the opposite direction that the player was running.</span>
The bike is maintaining "constant velocity". He's moving at 15 m/s when we see him for the first time, 15 m/s later that day, and 15 m/s next week.
The car starts from zero, and goes 4.0 m/s FASTER each second. After one second, it's going 4.0 m/s. After 2 seconds, it's going 8 m/s. And after 3 seconds, it's going 12 m/s.
This is the point at which the question wants us to compare them ... 3 seconds. The bike is moving at 15 m/s and the car has sped up to 12 m/s. <em>The bike is moving faster than the car.</em>
If we hung around and kept watching for another second, the car would then be moving at 16 m/s, and would be moving faster than the bike. But we lost interest after answering the question, and we left at 3 seconds.
We want to know what does the fact that Mercury has no atmosphere tell us. Since Mercury has no atmosphere it cant reflect a lot of sunlight that is hitting its surface. Its constantly being hit by solar wind. So Mercury reflects a small percentage of the sunlight that strikes it.