I believe number 4 I could be wrong but I think it’s 4
Answer:
0.05 mg / gallon
Explanation:
mass of chemecila coming in per minute = 50*10 = 500 mg/min
at a time t min , M = mass of chemical = 500*t mg
conecntartion of chemecal = 500t/10000 = 0.05 mg / gallon
Answer:
The annual operating cost of the refrigerator is $102.78.
Explanation:
Power consumed by the refrigerator = 247 W = 247/1000 = 0.247 kW
Daily operation of the refrigerator = 19 hours
Annual operation of the refrigerator = 365 × 19 = 6,935 hours
Annual energy consumed = 0.247 kW × 6,935 hours = 1712.945 kWh
1 kWh of electricity cost $0.06
1712.945 kWh will cost 1712.945 × $0.06 = $102.78
Annual operating cost = $102.78
Answer:
15.24°C
Explanation:
The quality of any heat pump pumping heat from cold to hot place is determined by its coefficient of performance (COP) defined as

Where Q_{in} is heat delivered into the hot place, in this case, the house, and W is the work used to pump heat
You can think of this quantity as similar to heat engine's efficiency
In our case, the COP of our heater is

Where T_{house} = 24°C and T_{out} is temperature outside
To achieve maximum heating, we will have to use the most efficient heat pump, and, according to the second law of thermodynamics, nothing is more efficient that Carnot Heat Pump
Which has COP of:

So we equate the COP of our heater with COP of Carnot heater

Rearrange the equation

Solve this simple quadratic equation, and you should get that the lowest outdoor temperature that could still allow heat to be pumped into your house would be
15.24°C