You perform an experiment to measure the speed of a car over time. The results are shown in the graph below. What is the best in
2 answers:
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Answer:
(a) Heat transfer to the environment is: 1 MJ and (b) The efficiency of the engine is: 41.5%
Explanation:
Using the formula that relate heat and work from the thermodynamic theory as: solving to Q_out we get:
this is the heat out of the cycle or engine, so it will be heat transfer to the environment. The thermal efficiency of a Carnot cycle gives us:
where T_Low is the lowest cycle temperature and T_High the highest, we need to remember that a Carnot cycle depends only on the absolute temperatures, if you remember the convertion of K=°C+273.15 so T_Low=150+273.15=423.15 K and T_High=450+273.15=723.15K and replacing the values in the equation we get:
do not forget to change grams to kilograms and if it were in centimeters convert them to meters.
Answer:
(a) Total time will be 8.05 hour
(B) Total cost will be $417.6
Explanation:
We have given dryer uses 16 A of current so current i = 16 A
Voltage V = 240 volt
Time t = 45 minutes =45×60 = 2700 sec
So power P = VI = 240×16 = 3840 W
So energy E = power×time = 3840×45×60 = 9396 KJ
(A) Now current in the computer i = 2.7 A
Voltage V = 120 V
So power P = 120×2.7 = 324 W
Now computer is using energy of dryer
So time by which it will use energy is
So time will be 8.05 hour
(b) Cost per kilowatt is $0.12
So total cost =3480×0.12 = $417.6