Answer:
a) C.M 
b) 
Explanation:
The center of mass "represent the unique point in an object or system which can be used to describe the system's response to external forces and torques"
The center of mass on a two dimensional plane is defined with the following formulas:
Where M represent the sum of all the masses on the system.
And the center of mass C.M 
Part a
represent the masses.
represent the coordinates for the masses with the units on meters.
So we have everything in order to find the center of mass, if we begin with the x coordinate we have:
C.M
Part b
For this case we have an additional mass 
and we know that the resulting new center of mass it at the origin C.M 
and we want to find the location for this new particle. Let the coordinates for this new particle given by (a,b)
If we solve for a we got:
And solving for b we got:
So the coordinates for this new particle are:
1. New moon
This is because the moon comes between the Earth and sun and this is only possible during its new moon phase.
2. Full moon
This is because the Earth comes between the Moon and the sun and the effect is only visible when there is a full moon.
3. Corona
The corona is the outer layer and is the only one visible when there is an eclipse.
Complete question:
Consider the hypothetical reaction 4A + 2B → C + 3D
Over an interval of 4.0 s the average rate of change of the concentration of B was measured to be -0.0760 M/s. What is the final concentration of A at the end of this same interval if its concentration was initially 1.600 M?
Answer:
the final concentration of A is 0.992 M.
Explanation:
Given;
time of reaction, t = 4.0 s
rate of change of the concentration of B = -0.0760 M/s
initial concentration of A = 1.600 M
⇒Determine the rate of change of the concentration of A.
From the given reaction: 4A + 2B → C + 3D
2 moles of B ---------------> 4 moles of A
-0.0760 M/s of B -----------> x
⇒Determine the change in concentration of A after 4s;
ΔA = -0.152 M/s x 4s
ΔA = -0.608 M
⇒ Determine the final concentration of A after 4s
A = A₀ + ΔA
A = 1.6 M + (-0.608 M)
A = 1.6 M - 0.608 M
A = 0.992 M
Therefore, the final concentration of A is 0.992 M.
v2 = v1 + at
60 = v1 + 4*10 v1 = 20 m/s
