A student buys a 5000 Btu window air conditioner for his apartment bedroom. He monitors it for one hour on a hot day and determi
nes that it operates approximately 60 percent of the time (duty cycle 5 60 percent) to keep the room at nearly constant temperature. (a) Showing all your work and using unity conversion ratios, calculate the rate of heat transfer into the bedroom through the walls, windows, etc. in units of Btu/h and in units of kW. (b) If the energy efficiency ratio (EER) of the air conditioner is 9.0 and electricity costs 7.5 cents per kilowatt-hr, calculate how much it costs (in cents) for him to run the air conditioner for one hour.
1 answer:
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Answer:
Work done = 13605.44
Explanation:
Data provided in the question:
For elongation of 2.1 cm (0.021 m) work done by the spring is 3.0 J
The relation between Energy (U) and the elongation (s) is given as:
U = ................(1)
where,
k is the spring constant
on substituting the valeus in the above equation, we get
3.0 =
or
k = 13605.44 N/m
now
for the elongation x = 2.1 + 4.1 = 6.2 cm = 0.062 m
using the equation 1, we have
U =
or
U = 26.149 J
Also,
Work done = change in energy
or
W = 26.149 - 3.0 = 23.149 J