Answer:
Object in motion: By the Newton's first law about inertia, an object in motion tends to keep in motion, unless an external force act on it.
Object at rest: By the Newton's first law about inertia, an object at rest tends to keep at rest, unless an external force act on it.
William Parsons was the first astronomer to show that spiral nebulae have large Doppler shifts.
<h3>What are Spiral nebulae?</h3>
- In space, a nebula is a huge cloud of gas and dust. Some nebulae, including multiple nebulae, are made of gas and dust that have been released from the explosion of a dead star called a supernova. There are other nebulae that are star-forming regions.
- Edwin Hubble began observing Cepheid variables in many spiral nebulae, including the alleged Andromeda Nebula, in 1923, demonstrating that they are, in fact, full-fledged galaxies outside our own. Since then, the phrase spiral nebula has lost favor.
- One group of astronomers believed that spiral nebulae were parts of our Milky Way galaxy, whereas the other group believed that these objects were actual galaxies that were outside of the Milky Way galaxy.
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Answer:
Explanation:
The artificial gravity generated by the rotating space station is the same centripetal acceleration due to the rotational motion of the station, which is given by:
Here, r is the radius and v is the tangential speed, which is given by:
Here 
is the angular velocity, we replace (2) in (1):
Recall that 
.
Solving for :
Answer:
4. since they are based on natural ecosystems have often resulted in alteration and destruction of natural systems
Explanation:
this is because agriculture leads to loss of habitats, loss of nutrients from the soil, it has also lead to the use of chemicals which are harmful to the environment as pesticides, and all this destroys natural systems
