Asked by Ricky
#1.) A wind turbine has a Cp of 0.42 and extracts 50 kW of power when the wind velocity is 25 m/sec. How long are the blades? (ρ = 1.2 kg/m3)
#2.) An electric hot water heater is used to heat 30 gallons of water from 20 °C to 45 °C.
a. What heat energy is required to increase its temperature?
b. What electric energy (still in Joules) is required if the efficiency is 98%?
c. If this heat energy flows into the water a constant rate over a 30 minute period, what power is
required over this period?
d. If this power is delivered by a resistive hot water heating element using a 240 V source, what must the resistance of the heating element be?
#2.) An electric hot water heater is used to heat 30 gallons of water from 20 °C to 45 °C.
a. What heat energy is required to increase its temperature?
b. What electric energy (still in Joules) is required if the efficiency is 98%?
c. If this heat energy flows into the water a constant rate over a 30 minute period, what power is
required over this period?
d. If this power is delivered by a resistive hot water heating element using a 240 V source, what must the resistance of the heating element be?
Answers
Answered by
bobpursley
heattoheatwater=masswater*specific*(45-20)
figure mass water from volume and denstity, look up specific heat.
if eff is .98, then energy=heat/.98
power=heateneryg/timeinseconds
R=V^2/energy
figure mass water from volume and denstity, look up specific heat.
if eff is .98, then energy=heat/.98
power=heateneryg/timeinseconds
R=V^2/energy
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.