Answer:Alpha decay, type of radioactive disintegration in which some unstable atomic nuclei dissipate excess energy by spontaneously ejecting an alpha particle.
Explanation:
The age of earth is b) 4.5 million years old
It is believed that earth is 4.5 million years old.
The radiometric age dating of earth meteorite content specifies the earth to be 4.5 million years old.
The formation of Earth is believed to have started shortly after the meteorites and nutrient inclusions were formed. It is challenging to differentiate between the ages of Earth and the oldest rocks since the duration of this accretion process is yet uncertain, and estimates from various accretion theories range from a few million with about 100 million years.
The oldest rocks on Earth that are visible at the surface are groupings of minerals, making it difficult to determine their exact age.
Due to the chemical makeup of rock minerals, some elements are found but not others; yet, in sedimentary deposits radioactive isotopes, the radioactive decay process over path to a successful strange elements.
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Answer:
The maximum speed at which the car can safety travel around the track is 18.6m/s.
Explanation:
Since the car is in circular motion, there has to be a centripetal force 
. In this case, the only force that applies for that is the static frictional force 
between the tires and the track. Then, we can write that:
And since 
and 
, we have:
Now, if we write the vertical equation of motion of the car (in which there are only the weight and the normal force), we obtain:
Substituting this expression for 
and solving for 
, we get:
Finally, plugging in the given values for the coefficient of friction and the radius of the track, we have:
It means that in its maximum value, the speed of the car is equal to 18.6m/s.
