1. The Prandtl number, Ner, is a dimensionless group important in heat transfer
ID: 700943 • Letter: 1
Question
1. The Prandtl number, Ner, is a dimensionless group important in heat transfer calculations and defined as Gm/k where G is the heat capacity of a fluid, m is the fluid viscosity, and k is the thermal conductivity. For a particular fluid, 0.483 J/(g°C), 0.679 W/(m°C), and 1436 lb/(ft h). Estimate the value of without using a calculator (remember, it is dimensionless), showing your calculations; then determine it with a calculator. 2. How much money would you have if someone gave you a stack of $20 bills 10 stories tall-show your work leading to your estimate? 3. Calculate the following logo(100)- log:o 10000) logo(10000000)'= 4, Calculate the following reporting the result in 10% 10-106-10-10 1010-10-10-10-31= 5. Convert 5.3°C to Kelvin. Write your answer in scientific notation with the appropriate number of significant figures. (Note Kelvin = °C +273.15) 6. Convert 254 cm to inches. Write your answer in scientific notation with the appropriate number of significant figures. (Note 1 inch 2.54 cm)Explanation / Answer
Ans 1
Specific heat capacity
Cp = 0.483 J/gC = 0.483*10^3 J/kg-C
Thermal conductivity
k = 0.679 W/m-C
Viscosity
m = 1436 lb/ft-h = 0.000413 x 1436 kg/m-s
= 0.5936 kg/m-s
Npr = 0.483*10^3 x 0.5936/0.679
= 422.25
Ans 3
Log 100 = log (10^2) = 2 log 10 = 2
Log 10000 = log (10^4) = 4 log 10 = 4
Log 10000000 = log (10^7) = 7 log 10 = 7
Ans 4
In the multiples, the power are added
10^6 x 10^6 x 10^3 x 10^-3 (= 6 +6 +3 - 3 = 12)
= 10^12
10^10 x 10^-6 x 10^34 x 10^-31 (= 10 - 6 +34 - 31 = 7)
= 10^7
Ans 5
T in K = T in °C + 273.15
= 5.3°C + 273.15
= 278.45 K
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