Answer:
(d) they are transmitted using digital signals
Explanation:
i just did the quiz an got it right
 
        
                    
             
        
        
        
Answer:
First, as you may know, the light travels at a given velocity.
In vaccum, this velocity is c = 3x10^8 m/s.
And we know that:
distance = velocity*time
Now, if some object (like a star ) is really far away, the light that comes from that star may take years to reach the Earth.
This means that the images that the astronomers see today, actually happened years and years ago (So the night sky is like a picture of the "past" of the universe)
Also, for example, if an astronomer sees some particular thing, he can apply a model (a "simplification" of some phenomena that is used to simplify it an explain it) and with the model, the scientist can infer the information of the given thing some time before it was seen.
 
        
             
        
        
        
This assumes that the wave has velocity c (is light).
 
        
        
        
Answer:
259.62521 seconds
Explanation:
 = Mass of astronaut = 87 kg
 = Mass of astronaut = 87 kg
 = Mass of wrench = 0.57 kg
 = Mass of wrench = 0.57 kg
 = Velocity of astronaut
 = Velocity of astronaut
 = Velocity of wrench = 22.4 m/s
 = Velocity of wrench = 22.4 m/s
Here, the linear momentum is conserved

Time = Distance / Speed

The time taken to reach the ship is 259.62521 seconds