Answer:
Explanation:
given data:
innner radius r_i = = 5cm
outer radius r_0 = 7 cm
temperature at outer surface = 80 degree celcius
temperature at inner surface = 100 degree celcius
thermal resistance per unit length is given as
heat loss rate per unit length 
q = 373.474 K
1) for pure COPPER
k = 387 W/m degree celcius
q = 373.474 * 387 = 144534.438 W
2) for pure ALUMINIUM
k = 200 W/m degree celcius
q = 373.474 * 200 = 74694.84 W
3)
1) for pure IRON
k = 62W/m degree celcius
q = 373.474 * 62 = 23155.416 W
Answer:
num_users = (update_direction == 3) ? (++num_users) : (--num_users);
Explanation:
A. Using the regular if..else statement, the response to the question would be like so;
if (update_direction == 3) {
++num_users; // this will increment num_users by 1
}
else {
-- num_users; //this will decrement num_users by 1
}
Note: A conditional expression has the following format;
<em>testcondition ? true : false;</em>
where
a. <em>testcondition </em>is the condition to be tested for. In this case, if update_direction is 3 (update_direction == 3).
b. <em>true </em>is the statement to be executed if the <em>testcondition</em> is true.
c. false is the statement to be executed it the <em>testcondition</em> is false.
B. Converting the above code snippet (the if..else statement in A above) into a conditional expression statement we have;
num_users = (update_direction == 3) ? (++num_users) : (--num_users);
<em>Hope this helps!</em>
Answer:
a) Thermal conductivity of skin: 
b) Temperature of interface: 
Heat flux through skin: 
Explanation:
a)
Where: 
is thermal conductivity of a material, 
is heat flux through a material, 
is the thickness of the material, 
is the temperature on the first side and 
is the temperature on the second side
b)
The heat flux between both surfaces is constant, assuming the temperature is maintained at each surface.
Answer:
The maximum discharge rate of water is 4.6 L/s
Explanation:
Given data:
d=diameter=8 m
h=height=3 m
The mathematical expression for the theoritical velocity is:
The maximum discharge can be calculate by:
Here
Cd=coefficient of discharge=0.855
Answer:
The heat loss rate through one of the windows made of polycarbonate is 252W. If the window is made of aerogel, the heat loss rate is 16.8W. If the window is made of soda-lime glass, the heat loss rate is 1190.4W.
The cost associated with the heat loss through the windows for an 8-hour flight is:
For aerogel windows: $17.472 (most efficient)
For polycarbonate windows: $262.08
For soda-lime glass windows: $1,238.016 (least efficient)
Explanation:
To calculate the heat loss rate through the window, we can use a model of heat transmission by conduction throw flat wall. Using unidimensional Fourier law:
In this case:
If we replace the data provided by the problem we get the heat loss rate through one of the windows of each material (we only have to change the thermal conductivities).
To obtain the thermal conductivity of the soda-lime glass we use the graphic attached to this answer (In this case for soda-lime glass k₃₀₀=0.992w/m·K).
To calculate the cost associated with the heat loss through the windows for an 8-hour flight we use this formula (using the heat loss rate calculated in each case):
