Answer:
Technician B
Explanation:
Resistance, 
where V is the voltage and I is the current in amps
Therefore, 
Power=VI=12*12=144 W
Therefore, the power is 144 W and resistance is 1 Ohm. This implies that technician A is wrong while technician B is correct
Answer:
79 kW.
Explanation:
The equation for enthalpy is:
H2 = H1 + Q - L
Enthalpy is defined as:
H = G*(Cv*T + p*v)
This is specific volume.
The gas state equation is:
p*v = R*T (with specific volume)
The specific gas constant for air is:
287 K/(kg*K)
Then:
T1 = 60 + 273 = 333 K
T2 = 200 + 273 = 473 K
p1*v1 = 287 * 333 = 95.6 kJ/kg
p2*v2 = 287 * 473 = 135.7 kJ/kg
The Cv for air is:
Cv = 720 J/(kg*K)
So the enthalpies are:
H1 = 0.8*(0.72 * 333 + 95.6) = 268 kW
H2 = 0.8*(0.72 * 473 + 135.7) = 381 kW
Ang the heat is:
Q = 34 kW
Then:
H2 = H1 + Q - L
381 = 268 + 34 - L
L = 268 + 34 - 381 = -79 kW
This is the work from the point of view of the air, that's why it is negative.
From the point of view of the machine it is positive.
Answer:
Explanation:
Let assume that changes in gravitational potential energy can be neglected. The fire hose nozzle is modelled by the Bernoulli's Principle:
The initial pressure is:
The speed at outlet is:
![v=\frac{(250\,\frac{gal}{min} )\cdot (\frac{3.785\times 10^{-3}\,m^{3}}{1\,gal} )\cdot(\frac{1\,min}{60\,s} )}{\frac{\pi}{4}\cdot [(1.125\,in)\cdot(\frac{0.0254\,m}{1\,in} )]^{2} }](https://tex.z-dn.net/?f=v%3D%5Cfrac%7B%28250%5C%2C%5Cfrac%7Bgal%7D%7Bmin%7D%20%29%5Ccdot%20%28%5Cfrac%7B3.785%5Ctimes%2010%5E%7B-3%7D%5C%2Cm%5E%7B3%7D%7D%7B1%5C%2Cgal%7D%20%29%5Ccdot%28%5Cfrac%7B1%5C%2Cmin%7D%7B60%5C%2Cs%7D%20%29%7D%7B%5Cfrac%7B%5Cpi%7D%7B4%7D%5Ccdot%20%5B%281.125%5C%2Cin%29%5Ccdot%28%5Cfrac%7B0.0254%5C%2Cm%7D%7B1%5C%2Cin%7D%20%29%5D%5E%7B2%7D%20%7D)
The initial pressure is:
