Answer:
0.5 g
Explanation:
The half-life of a radioactive isotope is the time it takes for a certain amount of that isotope to halve.
In this case, we have an isotope of Americium-241, which has a half-life of
This means that after 1 half-life (432 years), there will be an amount of americium equal to half its initial amount.
In this problem, the initial amount of americium is
Therefore, after 432 years (1 half-life), the amount of americium left will be half:
Answer:
A) Must be done 19806.62 joules of work.
B) The average power is 1320.44 Watts.
Explanation:
A) First, we're going to use the work-energy theorem that states total work (
) done on an object is equal to the change in its kinetic energy (
):
(1)
So, all we must do is to find the change on kinetic energy. Because we're working with rotational body, we should use the equation 
for the kinetic energy so:
(2)
with 
the initial angular velocity, 
the final angular velocity (is zero because the wheel stops) and I the moment of inertia that for a thin hoop is 
, using those on (2)
(3)
By (3) on (1):
B) Average power is work done divided by the time interval:
NOTE: We use the relation 
to convert 280 rev/min(rpm) to 29.32 rad/s
When the core temperature rises, stars start burning helium to carbon. Hydrogen and helium are fused in a shell surrounding the core, raising the temperature.
The most prevalent method of generating energy in the cosmos is hydrogen fusion. The gravitational force is utilised to fuse hydrogen at the centres of our Sun and other stars, where it has a density more than 70 times greater than that of steel. Thus, all of the heat and light on earth comes from fusion. Helium is a chemical element with the atomic number 2 and the symbol He. The first member of the noble gas group in the periodic table, it is a colourless, odourless, tasteless, inert, monatomic gas that is not harmful.
Learn more about gravitational force here
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You are correct, the answer is C.
Good insulators are materials that do not allow heat, electricity, light or sound pass through easily. Materials like steel and silver (which are metals) are not good insulators because they make good conductors. They easily allow heat, electricity and the like pass through them.
Thus, the answer is letter C. Rubber.
