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



Answer:
F = 1618.65[N]
Explanation:
To solve this problem we use the following equation that relates the mass, density and volume of the body to the floating force.
We know that the density of wood is equal to 750 [kg/m^3]
density = m / V
where:
m = mass = 165[kg]
V = volume [m^3]
V = m / density
V = 165 / 750
V = 0.22 [m^3]
The floating force is equal to:
F = density * g * V
F = 750*9.81*0.22
F = 1618.65[N]
Efficiency η of a Carnot engine is defined to be:
<span>η = 1 - Tc / Th = (Th - Tc) / Th </span>
<span>where </span>
<span>Tc is the absolute temperature of the cold reservoir, and </span>
<span>Th is the absolute temperature of the hot reservoir. </span>
<span>In this case, given is η=22% and Th - Tc = 75K </span>
<span>Notice that although temperature difference is given in °C it has same numerical value in Kelvins because magnitude of the degree Celsius is exactly equal to that of the Kelvin (the difference between two scales is only in their starting points). </span>
<span>Th = (Th - Tc) / η </span>
<span>Th = 75 / 0.22 = 341 K (rounded to closest number) </span>
<span>Tc = Th - 75 = 266 K </span>
<span>Lower temperature is Tc = 266 K </span>
<span>Higher temperature is Th = 341 K</span>
Time taken by the water balloon to reach the bottom will be given as

here we know that


now by the above formula



now in the same time interval we can say the distance moved by it will be


so it will fall at a distance 15.7 m from its initial position