Answer:
Once used as a energy source they cannot be charged/used again.
Explanation:
About 13.7 billion years ago
The Big Bang Theory states that the universe started about 13.7 billion years ago, and before that, everything was in 1 singularity.
Answer:
False
Explanation:
Becuase the average amu of 40 is represented
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:

The beginning of the Phanerozoic is marked by the development of hard body parts, such as shells and bones.