What is the efficiency of a device that takes in 400 J of heat and does 120 J
2 answers:
The efficiency of the device is 30 %
Explanation:
The efficiency of a heat engine is given by:
where
W is the work done by the engine
is the heat in input to the engine
For the device in this problem, we have:
W = 120 J is the work done
is the heat in input
Substituting, we find the efficiency:
which corresponds to an efficiency of 30%.
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The cost of excavating a space of 84 ft long, 42 ft wide, and 9 ft deep is $45864
Information about the problem:
- Space long= 84 ft
- Space wide= 42 ft
- Space deep= 9 ft
- Cost by yard3 = $39/yd3
- Total cost= ?
To solve this problem, we have to state the equation using the information of the problem:
Calculating the volume of the total space:
space volume = space long * space wide * space deep
space volume = 84 ft * 42 ft * 9 ft
space volume = 31752 ft3
By converting the volume from ft3 to yd3, we have:
31752 ft3 * (0,037037 yd3 / 1 ft3) = 1176 yd3
Calculating the cost of excavating the volume space:
Total cost = space volume * cost by yard3
Total cost = 1176 yd3 * $39/yd3
Total cost = $45864
<h3>What is volume?</h3>It is the space occupied by a body, it is calculated by multiplying its dimensions, for example: length, height and width.
Learn more about volume at: brainly.com/question/12628341
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