Answer:
Part a)

Part b)

Explanation:
Part a)
change in the energy due to decay of photon is given as

here we know that

now we have



Part b)
While electron return to its ground state it will emit a photon of energy 2/3rd of the total energy
so we have


now to find the wavelength we have



To solve the problem it is necessary to apply the concepts related to the conservation of energy through the heat transferred and the work done, as well as through the calculation of entropy due to heat and temperatra.
By definition we know that the change in entropy is given by

Where,
Q = Heat transfer
T = Temperature
On the other hand we know that by conserving energy the work done in a system is equal to the change in heat transferred, that is

According to the data given we have to,




PART A) The total change in entropy, would be given by the changes that exist in the source and sink, that is



On the other hand,



The total change of entropy would be,



Since
the heat engine is not reversible.
PART B)
Work done by heat engine is given by



Therefore the work in the system is 100000Btu
Answer:
Explanation:
Given
Original Frequency 
apparent Frequency 
There is change in frequency whenever source move relative to the observer.
From Doppler effect we can write as

where
apparent frequency
v=velocity of sound in the given media
velocity of source
velocity of observer
here 




i.e.fork acquired a velocity of 
distance traveled by fork is given by

where v=final velocity
u=initial velocity
a=acceleration
s=displacement



The solution for this problem would be:(10 - 500x) / (5 - x)
so start by doing:
x(5*50*2) - xV + 5V = 0.02(5*50*2)
500x - xV + 5V = 10
V(5 - x) = 10 - 500x
V = (10 - 500x) / (5 - x)
(V stands for the volume, but leaves us with the expression for x)
Answer:
Spring constant, k = 0.3 N/m
Explanation:
It is given that,
Force acting on DNA molecule, 
The molecule got stretched by 5 nm, 
Let k is the spring constant of that DNA molecule. It can be calculated using the Hooke's law. It says that the force acting on the spring is directly proportional to the distance as :



k = 0.3 N/m
So, the spring constant of the DNA molecule is 0.3 N/m. Hence, this is the required solution.