It all comes to the doppler effect, the red shift means that the galaxy is moving away from us. The redshift is a result from the doppler effect, so as the galaxy moves away the wavelength expands, increasing the wavelength which responds to the red light. 
 
        
                    
             
        
        
        
Answer:
    μ = 0.37
Explanation:
For this exercise we must use the translational and rotational equilibrium equations.
We set our reference system at the highest point of the ladder where it touches the vertical wall. We assume that counterclockwise rotation is positive
let's write the rotational equilibrium
            W₁  x/2 + W₂ x₂ - fr y = 0
where W₁ is the weight of the mass ladder m₁ = 30kg, W₂ is the weight of the man 700 N, let's use trigonometry to find the distances
              cos 60 = x / L
where L is the length of the ladder
               x = L cos 60
             sin 60 = y / L
            y = L sin60
 the horizontal distance of man is
             cos 60 = x2 / 7.0
             x2 = 7 cos 60
we substitute
          m₁ g L cos 60/2 + W₂ 7 cos 60 - fr L sin60 = 0
          fr = (m1 g L cos 60/2 + W2 7 cos 60) / L sin 60
let's calculate
          fr = (30 9.8 10 cos 60 2 + 700 7 cos 60) / (10 sin 60)
          fr = (735 + 2450) / 8.66
          fr = 367.78 N
the friction force has the expression
          fr = μ N
write the translational equilibrium equation
          N - W₁ -W₂ = 0
          N = m₁ g + W₂
          N = 30 9.8 + 700
          N = 994 N
we clear the friction force from the eucacion
         μ = fr / N
         μ = 367.78 / 994
         μ = 0.37
 
        
             
        
        
        
¡Hellow!
For this problem, first, lets convert the seconds in hours:
5,4x10³ 5400
 5400
h = sec / 3600
h = 5400 s / 3600
h = 1,5 
Let's recabe information:
d (Distance) = 386 km
t (Time) = 1,5 h
v (Velocity) = ?
For calculate velocity, let's applicate formula:
                                                     
Reeplace according we information:
386 km = v * 1,5 h
v = 386 km / 1,5 h
v = 257,33 km/h
The velocity of the train is of <u>257,33 kilometers for hour.</u>
<u></u>
Extra:
For convert km/h to m/s, we divide the velocity of km/h for 3,6:
m/s = km/h / 3,6
Let's reeplace:
m/s = 257,33 km/h / 3,6
m/s = 71,48
¿Good Luck?
 
        
             
        
        
        
Answer:
D
Explanation:
The answer is Niels Bohr's planetary model, the difference between this model and all of the other models is that the Bohr's PM Is more of layers of 
Nucleus - Protons and Neutrons
Electron Orbital - Period 1 Elements
2 electrons
Electron Orbital - Period 2 Elements
8 electrons
Electron Orbital - Period 3 Elements
8 electrons
If that made sense-