Answer:
The center of mass of the Earth-Moon system is 4.673 kilometers away from center of Earth.
Explanation:
Let suppose that planet and satellite can be treated as particles. The masses of Earth and Moon (
, 
) are 
 and 
, respectively. The distance between centers is 384,403 kilometers. The location of the center of mass can be found by using weighted averages:

If 
 and 
, then:


The center of mass of the Earth-Moon system is 4.673 kilometers away from center of Earth.
 
        
             
        
        
        
Answer:
 v₂ = 7/ (0.5)= 14 m/s
Explanation:
Flow rate of the fluid
Flow rate is the amount of fluid that circulates through a section of the pipeline (pipe, pipeline, river, canal, ...) per unit of time.
The formula for calculated the flow rate is:
Q= v*A Formula (1)
Where :
Q is the Flow rate (m³/s) 
A is the cross sectional area of a section of the pipe (m²)
 v is the speed of the fluid in that section (m/s)
Equation of continuity
The volume flow rate Q for an incompressible fluid at any point along a pipe is the same as the volume flow rate at any other point along a pipe:
Q₁= Q₂ 
Data
A₁ = 2m² : cross sectional area 1
v₁ = 3.5 m/s : fluid speed through A₁ 
A₂ = 0.5 m² : cross sectional area 2
Calculation of the fluid speed through A₂
We aply the equation of continuity:
Q₁= Q₂ 
We aply the equation of Formula (1):
v₁*A₁= v₂*A₂ 
We replace data
(3.5)*(2)= v₂*(0.5)
7 = v₂*(0.5)
 v₂ = 7/ (0.5)
 v₂ =  14 m/s