1. its must be B and 2. must be C
Answer:
Work out = 28.27 kJ/kg
Explanation:
For R-134a, from the saturated tables at 800 kPa, we get
= 171.82 kJ/kg
Therefore, at saturation pressure 140 kPa, saturation temperature is
= -18.77°C = 254.23 K
At saturation pressure 800 kPa, the saturation temperature is
= 31.31°C = 304.31 K
Now heat rejected will be same as enthalpy during vaporization since heat is rejected from saturated vapour state to saturated liquid state.
Thus, 
= = 171.82 kJ/kg
We know COP of heat pump
COP = 
= 
= 6.076
Therefore, Work out put, W = 
= 171.82 / 6.076
= 28.27 kJ/kg
Ideal gas law:
PV = nRT
P = pressure, V = volume, n = # of moles, R = gas constant, T = temperature
Equipartition theorem:
Each degree of freedom that a molecule has adds 0.5kT to its total internal energy where k = Boltzmann's constant and T = temperature
2nd law of thermodynamics:
A set of governing principles that restrict the direction of net heat flow (always hot to cold, heat engines are never 100% efficient, entropy always tends to increase, etc)
Clearly the answer is Choice A
The first thing you should do is calculate the work done when climbing the stairs. This work by definition will be given by:
W = F * d
W = (m * g) * (d)
W = ((71) * (9.8)) * (3) = 2087.4J
Then, you can calculate the power that in this case is given by
P = W / t
P = (2087.4) / (10) = 208.74W
To have the result in HP we use the fact that 1HP = 746W
P = (208.74) / (746)
P = 0.28 HP
answer
the power you produce in running up a flight of stairs is 0.28 HP
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