Answer: 71.72 days
Explanation:
This problem can be solved using the <u>Radioactive Half Life Formula: </u>
(1)
Where:
is the final amount of Iodine-131
is the initial amount of Iodine-131
is the time elapsed
is the half life of Iodine-131
Knowing this, let's substitute the values and find from (1):
(2)
(3)
Applying natural logarithm in both sides:
(4)
(5)
Finding :
(a) 
The change in potential energy of the electron is given by:
where
is the magnitude of the electron's charge
is the magnitude of the electric field
d = 520 m is the distance through which the electron has moved
Substituting into the equation, we find
(b) 78 kV
The potential difference the electron has moved through is given by
where
is the magnitude of the electric field
d = 520 m is the distance through which the electron has moved
Substituting into the equation, we find
Interstellar gas clouds are common in many galaxy, like the Orion nebulae which many young stars are being born. A typical nebula is many light years in diameter and contains enough material mass to make several thousand stars the size of our sun. The majority of the gas in nebulae consist of molecules of hydrogen and helium-but most nebulae also contain atoms of other elements. All known element in our periodic table is also being made inside this crucible of this immense hot gas. The source of the organic molecules is still a mystery. Irregularities in the density of the gas causes a net gravitational force that pull the gas molecules close together.
Taking shorter showers, turning off the lights when you aren't in a room, use energy efficient lightbulbs like LED's, use the air conditioning only when you really need it, and use the heat less in the winter.
