Answer:
Thus the time taken is calculated as 387.69 years
Solution:
As per the question:
Half life of = 28.5 yrs
Now,
To calculate the time, t in which the 99.99% of the release in the reactor:
By using the formula:
where
N = No. of nuclei left after time t
= No. of nuclei initially started with
(Since, 100% - 99.99% = 0.01%)
Thus
Taking log on both the sides:
t = 387.69 yrs
<u>Answer:</u> The energy gained by the air molecules is 0.011 J.
<u>Explanation:</u>
Law of conservation of energy states that energy can neither be created nor be destroyed but it can only be transformed from one form to another form.
Here, the potential energy of the coffee filter is getting converted into kinetic energy of the coffee filter and some energy is lost by it which is gained by the air molecules in the form of kinetic energy.
So, calculating the potential energy of coffee filter, we use the equation:
P = mgh
where,
m = mass of coffee filter = 1.2 g = (Conversion used: 1 kg = 1000 g)
g = acceleration due to gravity =
h = height of coffee filter = 1 m
Putting values in above equation, we get:
where,
m = mass of coffee filter = 1.2 g =
v = speed of coffee filter = 0.8 m/s
Putting values in above equation, we get:
As, energy lost by coffee filter = energy gained by air molecules
So, energy lost by coffee filter = Potential energy - Kinetic energy
Energy lost by coffee filter =
Hence, the energy gained by the air molecules is 0.011 J.