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>
Answer
given,
D = 50 mm = 0.05 m
d = 10 mm = 0.01 m
Force to compress the spring
F = 3160 N
stress correction factor from stress correction curve is equal to 1.1
now, calculation of corrected stress
= 442.6 Mpa
The tensile strength of the steel material of ASTM A229 is equal to 1300 Mpa
now,
since corrected stress is less than the 
hence, spring will return to its original shape.
Answer: 4.19 N
Explanation: In order to determinate the tension applied on the wire we have to calculate the electric force between the conductor spheres connected by the wire.
As the wire is a conductor the spheres are at same potential so we have:
V1=V2
V1=k*Q1/r1 and V2=k*Q2/r2
where r1=r2, then
Q1=Q2
so the electric force is given by:
F=k*Q^2/d^2 where d is the distance between the spheres.
Finally replacing the values, we have
F=9*10^9(41*10^-6)^2/(1.9)^2= 4.19 N
