Correct temperature is 80°F
Answer:
T_f = 38.83°F
Explanation:
We are given;
Volume; V = 8 ft³
Initial Pressure; P_i = 100 lbf/in² = 100 × 12² lbf/ft²
Initial temperature; T_i = 80°F = 539.67 °R
Time for outlet flow; t_o = 90 s
Mass flow rate at outlet; m'_o = 0.03 lb/s
Final pressure; P_f = 30 lbf/in² = 30 × 12² lbf/ft²
Now, from ideal gas equation,
Pv = RT
Where v is initial specific volume
R is ideal gas constant = 53.33 ft.lbf/°R
Thus;
v = RT/P
v_i = 53.33 × 539.67/(100 × 12²)
v_i = 2 ft³/lb
Formula for initial mass is;
m_i = V/v_i
m_i = 8/2
m_i = 4 lb
Now change in mass is given as;
Δm = m'_o × t_o
Δm = 0.03 × 90
Δm = 2.7 lb
Now,
m_f = m_i - Δm
Thus; m_f = 4 - 2.7
m_f = 1.3 lb
Similarly in above;
v_f = V/m_f
v_f = 8/1.3
v_f = 6.154 ft³/lb
Again;
Pv = RT
Thus;
T_f = P_f•v_f/R
T_f = (30 × 12² × 6.154)/53.33
T_f = 498.5°R
Converting to °F gives;
T_f = 38.83°F
Answer:
The heat transferred through the wall that day is 13728 BTUs
Explanation:
Here, we have the area of the wall given as
Area of wall = 2 × Length × Height + 2 × Width × Height
Length = 15 feet
Width = 11 Feet and
Height = 9 feet
Therefore, the area = 2×15×9 + 2×11×9 = 468 ft²
Temperature difference is given by
Average outside temperature - Wall temperature = 40 - 18 = 22 °F
Therefore the heat transferred through the wall that day (24 hours) at 18 sq.ft. hr/BTU is given by;
468 × 22 × 24/18 = 13728 = 13728 BTUs.
1 mA = 0.001 A
Therefore, 5 mA = 0.001 * 5
=0.005 A
Resistance = voltage / current
= 100 / 0.005
= 20000 ohms
Current = voltage / resistance
= 25 / 20000
= 0.00125 A (or) 1.25 mA
Answer:
Spring cannot return to its original, since a part of its deformation is <u>plastic</u>, not <u>elastic</u>.
Explanation:
Physically speaking, stress is equal to the axial force divided by effective transversal area of spring. In addition, springs have usually a linear relationship between stress and strain in <u>elastic region</u>, since they are made of ductile materials. Axial force is directly proportional to axial stress, which is also directly proportional to axial strain.
Then, if force is greater than force associated with elastic limit of the spring, then spring cannot return to its original, since a part of its deformation is <u>plastic</u>, not <u>elastic</u>.
-happiness
Explanation:
- Happiness is a result of desires.
- People are known to feel happy when some of their most important desires are fulfilled.
- If desire is not important, people feel only greater or less satisfaction. But at one level, desires and happiness are excluded because when some desires are fulfilled they are extinguished, and only the feeling of happiness slowly fades.
- Happiness should not be waited passively, it should not be expected that it will come from the outside through some happy event or that other people will make us happy through great love.
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