Mass extinction occur from natural disasters, such as a n asteroid hitting earth or a volcano errupting and spread ash everywhere.
It makes sense to measure geologic time between mass extinctions because after each mass extinction, there is almost no life left and the few left have to repopulate, which may lead way to new mutations and new varieties of plants and animals.
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D=Vot+1/2at^2
In this case, there is no initial y velocity so the term Vot=0 so d=1/2at^2
acceleration=acceleration due to gravity=-9.8m/s^2
It falls - 22cm or -0.22m
We have - 0.22=1/2(-9.8)t^2
t^2=(-0.44)/(-9.8)
t=sqrt[0.44/9.8]
where 
is the gravitational constant and is about 
:D
<span>For this particular problem, we use Ohm's Law. This law deals with the relation between
voltage and current in an ideal conductor. It states that: Potential difference
across a conductor is proportional to the current that pass through it. It is
expressed as V=IR. Using the equation, we can isolate I or the current to one side and the other terms to the other side. We calculate as follows:
V = IR
I = V/R
I = 12 V / 20 </span><span>Ω
I = 0.6 amperes
Therefore, the current that is flowing through the wire supplied with 12 V and having a resistance of 20 </span><span>Ω would be 0.6 amperes.</span>
