Answer:
50.005 kJ of heat is transferred by the system
Solution:
As per the question:
Mass of the closed system, m = 10 kg
Decrease in elevation, d = 50 m
Initial velocity, v = 15 m/s
Final velocity, v' = 30 m/s
Change in internal energy, dU = - 5 kJ/kg = - 5000(10 kg) = - 50000 J
As per the first thermodynamics' law:
dQ = dW + (dPE +dKE + dU) (1)
where
dQ = heat transfer change
dPE +dKE + dU = dE = change in the energy of the system
PE = Potential Energy
KE = Kinetic Energy
U = Internal energy
Now,
dPE = mgd = -
(Since, the elevation decreases and hence PE decreases)
dKE =
Work done, dW =
Therefore, using the respective energy values in eqn (1):