Answer:
<em>Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses.[1] All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-seque</em>
The heat energy transferred by the iron nail is 4680 J
Explanation:
The thermal energy transferred by a substance to another substance is given by the equation

where
m is the mass of the substance
C is its specific heat capacity
is its change in temperature
For the iron nail in this problem, we have:
m = 16 g


So, the amount of heat energy given off by the nail is

where the negative sign indicates that the heat is given off.
Learn more about specific heat capacity:
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Answer:
Part a)

Part b)

Part c)

Part d)

Explanation:
Part a)
While bucket is falling downwards we have force equation of the bucket given as

for uniform cylinder we will have

so we have


now we have




now we have


Part b)
speed of the bucket can be found using kinematics
so we have



Part c)
now in order to find the time of fall we can use another equation



Part d)
as we know that cylinder is at rest and not moving downwards
so here we can use force balance


