When the rock recrystallizes, the decay of Potassium-40 continues at a constant rate but the argon-40 cannot escape and the gas is trapped in the rock. In this method, the rocks are heated to the melting point, and any Ar-40 contained is released into the atmosphere. The age of a certain rock can be determined through the calculation of the ratio and the decay rate of K-40. In molten rocks, it produces the gas Argon (known as Argon-40).
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Through beta decay, it results in calcium-40 and this occurs in almost 90% of cases. Some of the radioactive isotope of Potassium, Potassium-40 (K-40) decays through a process of radiometric decay. This can be done by calculating the ratio of radioactive argon to radioactive potassium in the rock sample. This method is widely used in archeology, particularly in East Africa. Yet, it is not suitable to measure the age of rock 20,000 years before present. This is the most viable technique for dating old rocks because archeologists can use it to date rocks as much as 4 billion years old. The potassium-argon age method is another method widely used by archeologists and geologists to determine the time of origin of rocks. The date is usually callibrated with dendrochronology method to get a more absolute B.P. The rate of decrease is ½ the quantity at death every 5.730 years, the half life of C-14. The “present” is set at the year 1950 on the Gregorian calender. The date assigned to the sample successfully collected will initially be given as a raw B.P. With this method, the type of sample and the placement of it within a site are taken into account. The radiocarbon dating method is widely used to determine the age of remains of living organisms. Once the organism dies, the ratio of C-14 within its carcass starts to decrease. Animals eating those plants absorb Carbon-14 and the process of ingesting C-14 continues as long as the plants and animals are alive.
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The C-14 is attached to organic molecules through photosynthesis in plants and becomes part of their molecular makeup. The laws of radioactive decay hypothesize that once a living organism is dead, it does not interact with anything in its environment which would afffect the speed of decay of the unstable isotope of carbon 14.