In science, a force is a push or a pull. is it true or false ?
1 answer:
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Answer:
attached below
Explanation:
Answer:
the rate of entropy change of the air is -0.1342 kW/K
the assumptions made in solving this problem
- Air is an ideal gas.
- the process is isothermal ( internally reversible process ). the change in internal energy is 0.
- It is a steady flow process
- Potential and Kinetic energy changes are negligible.
Explanation:
Given the data in the question;
From the first law of thermodynamics;
dQ = dU + dW ------ let this be equation 1
where dQ is the heat transfer, dU is internal energy and dW is the work done.
from the question, the process is isothermal ( internally reversible process )
Thus, the change in internal energy is 0
dU = 0
given that; Air is compressed by a 40-kW compressor from P1 to P2
since it is compressed, dW = -40 kW
we substitute into equation 1
dQ = 0 + ( -40 kW )
dQ = -40 kW
Now, change in entropy of air is;
ΔS = dQ / T
given that T = 25 °C = ( 25 + 273.15 ) K = 298.15 K
so we substitute
ΔS = -40 kW / 298.15 K
ΔS = -0.13416 ≈ -0.1342 kW/K
Therefore, the rate of entropy change of the air is -0.1342 kW/K
the assumptions made in solving this problem
- Air is an ideal gas.
- the process is isothermal ( internally reversible process ). the change in internal energy is 0.
- It is a steady flow process
- Potential and Kinetic energy changes are negligible.
Answer:
hello attached is the free body diagram of the missing figure
Fr =
Explanation:
Average velocity is constant i.e V1 = V2 = V
The momentum equation for the flow in the Z - direction can be expressed as
-Fr + P1 Ac - P2 Ac = mB2V2 - mB1V1 ------- equation 1
Fr = horizontal force on the bolts
P1 = pressure of fluid at entrance
V1 = velocity of fluid at entrance
Ac = cross section area of the pipe
P2 and V2 = pressure and velocity of fluid at some distance
m = mass flow rate of fluid
B1 = momentum flux at entrance , B2 = momentum flux correction factor
Note; average velocity is constant hence substitute V for V1 and V2
equation 1 becomes
Fr = ( P1 - P2 ) Ac + mV ( 1 - 2 )
Fr = ( P1 - P2 ) Ac - mV ---------------- equation 2
equation for mass flow rate
m = <em>p</em>AcV
<em>p</em> = density of the fluid
insert this into equation 2 EQUATION 2 BECOMES
Fr = ( P1 - P2) Ac - <em>p</em>AcV^2
= Ac [ (P1 - P2) - pV^2 ] ---------- equation 3
Note Ac =
Equation 3 becomes
Fr = [ (P1 -P2 ) - pV^2 ] ------- relation for the horizontal force acting on the bolts
