Which of the following has to happen for Earth's shadow to fall on the moon?

Air at 400 kPa, 980 K enters a turbine operating at steady state and exits at 100 kPa, 670 K. Heat transfer from the turbine occ

Angelina_Jolie [31]

Answer:

a). $\frac{\dot{W}}{m}= 311$ kJ/kg

b). $\frac{\dot{\sigma _{gen}}}{m}=0.9113$ kJ/kg-K

Explanation:

a). The energy rate balance equation in the control volume is given by

$\dot{Q} - \dot{W}+m(h_{1}-h_{2})=0$

$\frac{\dot{Q}}{m} = \frac{\dot{W}}{m}+m(h_{1}-h_{2})$

$\frac{\dot{W}}{m}= \frac{\dot{Q}}{m}+c_{p}(T_{1}-T_{2})$

$\frac{\dot{W}}{m}= -30+1.1(980-670)$

$\frac{\dot{W}}{m}= 311$ kJ/kg

b). Entropy produced from the entropy balance equation in a control volume is given by

$\frac{\dot{Q}}{T_{boundary}}+\dot{m}(s_{1}-s_{2})+\dot{\sigma _{gen}}=0$

$\frac{\dot{\sigma _{gen}}}{m}=\frac{-\frac{\dot{Q}}{m}}{T_{boundary}}+(s_{2}-s_{1})$

$\frac{\dot{\sigma _{gen}}}{m}=\frac{-\frac{\dot{Q}}{m}}{T_{boundary}}+c_{p}ln\frac{T_{2}}{T_{1}}-R.ln\frac{p_{2}}{p_{1}}$

$\frac{\dot{\sigma _{gen}}}{m}=\frac{-30}{315}+1.1ln\frac{670}{980}-0.287.ln\frac{100}{400}$

$\frac{\dot{\sigma _{gen}}}{m}=0.0952+0.4183+0.3978$

$\frac{\dot{\sigma _{gen}}}{m}=0.9113$ kJ/kg-K

5 0

3 years ago

. A 13-g goldfinch has a speed of 8.5 m/s. What is its kinetic energy?

lesya692 [45]

PLEASE PRESS THE “Thanks!” BUTTON! :)
13 g —> 0.013 kg
KE = 1/2(m)(v)^2
KE = 1/2(0.013)(8.5)^2
KE = 0.47 J

3 0

2 years ago

Describe what happens to the system inside of a refrigerator or freezer in terms of heat transfer, work, and conservation of ene

Over [174]

Answer: A. Work is done on the system and heat is transferred from the system for a net decrease in internal energy.

Explanation:

A refrigerator is a device which dispenses heat from the close system to a warmer area or in the surrounding. By dispensing the heat the internal temperature of the refrigerator drops. The system of refrigerator violates the second law of thermodynamics. As it performs the work to cool the region instead of heating the region. The work is done on the system and the internal energy decreases and the heat energy is liberated to the surrounding area. A refrigerator is an open system.

6 0

2 years ago

What is the net force on a bag pulled down by gravity with a force of 18 newtons and pulled upward by a rope with a force of 18

VARVARA [1.3K]

Answer:

0 N.

Explanation:

Force: This can be defined as the product of mass and the acceleration of the body. The S.I unit of force is Newton (N).

The expression of net force when both force act in the different direction is given as

F' = W-F ........................ Equation 1

Where F' = Net force on the bag, W = gravitational force on the bag, F = Force acting upward on the bag

Given: W = 18 N, F = 18 N.

Substitute into equation 1

F' = 18-18

F' = 0 N.

Hence the net force = 0 N.

4 0

3 years ago

What is a circuit that only has one loop??

larisa86 [58]

Series :) is the answer

6 0

3 years ago