Answer: B, repetitive practice! hope this helps. :)
Explanation:
Answer:
D) 1.04 Btu/s from the liquid to the surroundings.
Explanation:
Given that:
flow rate (m) = 2 lb/s
liquid specific enthalpy at the inlet (
Btu/lb)
liquid specific enthalpy at the exit (
Btu/lb)
initial elevation (
)
final elevation (
)
acceleration due to gravity (g) = 32.174 ft/s²
= 3 Btu/s
The energy balance equation is given as:
![Q_{cv}-W{cv}+m[(h_1-h_2)+(\frac{V_1^2-V_2^2}{2})+g(z_1-z_2)]=0](https://tex.z-dn.net/?f=Q_%7Bcv%7D-W%7Bcv%7D%2Bm%5B%28h_1-h_2%29%2B%28%5Cfrac%7BV_1%5E2-V_2%5E2%7D%7B2%7D%29%2Bg%28z_1-z_2%29%5D%3D0)
Since kinetic energy effects are negligible, the equation becomes:
![Q_{cv}-W{cv}+m[(h_1-h_2)+g(z_1-z_2)]=0](https://tex.z-dn.net/?f=Q_%7Bcv%7D-W%7Bcv%7D%2Bm%5B%28h_1-h_2%29%2Bg%28z_1-z_2%29%5D%3D0)
Substituting values:
![Q_{cv}-(-3)+2[(40.09-40.94)+\frac{32.174(0-100)}{778*32.174} ]=0\\Q_{cv}+3+2[-0.85-0.1285 ]=0\\Q_{cv}+3+2(-0.9785)=0\\Q_{cv}+3-1.957=0\\Q_{cv}+1.04=0\\Q_{cv}=-1.04\\](https://tex.z-dn.net/?f=Q_%7Bcv%7D-%28-3%29%2B2%5B%2840.09-40.94%29%2B%5Cfrac%7B32.174%280-100%29%7D%7B778%2A32.174%7D%20%5D%3D0%5C%5CQ_%7Bcv%7D%2B3%2B2%5B-0.85-0.1285%20%5D%3D0%5C%5CQ_%7Bcv%7D%2B3%2B2%28-0.9785%29%3D0%5C%5CQ_%7Bcv%7D%2B3-1.957%3D0%5C%5CQ_%7Bcv%7D%2B1.04%3D0%5C%5CQ_%7Bcv%7D%3D-1.04%5C%5C)
The heat transfer rate is 1.04 Btu/s from the liquid to the surroundings.
Answer: (C) 9.14 . 10⁻³ Ω
Explanation:
The resistance of a resistor, is proportional to his length and inversely proportional to his area, being the proportionality constant a property of the material, called resistivity.
The resistivity is defined as the inverse of the electrical conductivity, which depends on the number of charge carriers and the mobility of these carriers, which is different for each material.
So, we can calculate the resistance as follows:
R = 1/σ . L / A, where:
σ = electrical conductivity, l= length of the wire , A = wire cross-section (assumed circular).
Replacing by the values, we can calculate R as follows:
R = 1/6.1. 10⁷ (Ω.m) . 8.1 m. / π (0.0043)² m / 4 = 9.14 . 10⁻³ Ω
