Answer:
Sounds cool.. but what do they do?
Explanation:
 
        
                    
             
        
        
        
The boundary between the crust and mantle is marked by a seismic-velocity discontinuity is called Mohorovicic discontinuity.
Mohorovicic discontinuity was discovered by Andrija Mohorovicic in 1909 who was a Croatian seismologist. He realized that the velocity of a seismic wave is related to the material's density where it is moving through. He decoded that the acceleration of the seismic waves that are observed within outer shell of the earth is a compositional change. Thus, the acceleration should be caused by a material of higher density.
 
        
                    
             
        
        
        
Answer:
Betelgeuse is 640 light years away from earth.
Explanation:
A light-year is an astronomical unit to measure the distance the light travels in a calendar year. 
If the light from a star takes 640 years to reach us, then that star its 640ly away from us.
Betelgeuse has been labeled as a Variant Star, which means that its brightness can fluctuate over the course of years, this has made difficult for astronomers to measure the exact distance of the star. Right now the star is estimated to be around 613 and 881ly away from earth, although, for the sake of your second question, we will take 640 years as our estimated value. 
In 1380 (640 years ago) the Battle of Kulikovo took place. A battle of remarkable importance to Russian history, in which the Russian army, led by Prince Dmitry of Moscow, defeated the Mongol army, defining a turning point in the Mongol dominance, and setting the bases for what Russia is today. 
 
        
                    
             
        
        
        
The orbiting speed of the satellite orbiting around the planet Glob is 60.8m/s.
To find the answer, we need to know about the orbital velocity a satellite.
<h3>What's the expression of orbital velocity of a satellite?</h3>
- Mathematically, orbital velocity= √(GM/r)
- G= gravitational constant= 6.67×10^(-11) Nm²/kg², M = mass of sun , r= radius of orbit
<h3>What's the orbital velocity of the satellite in a circular orbit with a radius of 1.45×10⁵ m around the planet Glob of mass 7.88×10¹⁸ kg?</h3>
- Here, M= 7.88×10¹⁸ kg, r= 1.45×10⁵ m
- Orbital velocity of the orbiting satellite = √(6.67×10^(-11)×7.88×10¹⁸/1.45×10⁵)
 = 60.8m/s
Thus, we can conclude that the speed of the satellite orbiting the planet Glob is 60.8m/s.
Learn more about the orbital velocity here:
brainly.com/question/22247460
#SPJ1
 
        
             
        
        
        
The frequency doesn't change as the wave crosses 
the boundary between one medium and another.