Solving Carnot Heat Problem: 1637.8BTU Answered

  • Thread starter Thread starter Windseaker
  • Start date Start date
  • Tags Tags
    Carnot Heat
AI Thread Summary
The discussion centers on calculating the heat extracted from a heat source by a heat engine connected to a 300-watt motor, operating at 40% efficiency for 4 hours. The calculations show that the total heat extracted is 1637.8 BTU, with the engine utilizing more heat energy than the work it produces. There is a debate about the use of BTU versus joules for heat measurement, with an emphasis on BTU being more common in residential contexts in the US. The time factor of 4 hours is confirmed to be relevant in the calculations. Overall, the focus is on understanding the efficiency and energy output of the heat engine.
Windseaker
Messages
45
Reaction score
0

Homework Statement


Problem: A heat engine is connected to a 300watt motor. If we power the motor for 4hrs and heat engine is 40% efficient,how much heat is extracted from heat source in?

Homework Equations


Given: Q= heat QC=waste heat QH=W+QC and Power=E/t or Work/t

The Attempt at a Solution

This is a diagram equation of heat.
QH-----l----->QC
l
l
V
300w

300W(3.412btu/1W)= 1023.6btu (4hr) = 4094.4 btuh
----- 4094.4btu(40%)=1637.8btuh
 
Physics news on Phys.org
The engine uses more heat energy than the work it yields: the work is 40 % of the heat: W=0.4*Q.

Do you really use btu units for heat instead of joule?

ehild
 
So, are you saying that time is not used here (4hrs)? its just the starting heat loss.

yes btu, this is more about residential usage in US.
 

Thread 'Rolling without slipping on a curved surface'

Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
View full post »
Thread 'Voltmeter readings for this circuit with switches'

Thread 'Voltmeter readings for this circuit with switches'

TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
View full post »
Thread 'Trying to understand the logic behind adding vectors with an angle between them'

Thread 'Trying to understand the logic behind adding vectors with an angle between them'

My initial calculation was to subtract V1 from V2 to show that from the perspective of the second aircraft the first one is -300km/h. So i checked with ChatGPT and it said I cant just subtract them because I have an angle between them. So I dont understand the reasoning of it. Like why should a velocity be dependent on an angle? I was thinking about how it would look like if the planes where parallel to each other, and then how it look like if one is turning away and I dont see it. Since...
View full post »

Similar threads

Carnot engine efficiency problem
Replies
3
Views
4K
Work done by a Carnot Engine. Melting ice
Replies
2
Views
3K
Thermodynamics problem involving engine efficiency
Replies
20
Views
3K
How Much Water Can a 1KW Carnot Engine Freeze in 5 Minutes?
Replies
3
Views
1K
What is the efficiency of a Carnot engine and the effectiveness of a heat pump?
Replies
1
Views
3K
Temperature in a Carnot heat engine
Replies
2
Views
3K
Thermal Question -- Carnot Engine
Replies
3
Views
2K
Efficiency of Stirling Cycle - Is it the same as the Carnot Engine?
Replies
14
Views
1K
How do temperature differences affect the work done in an ideal Carnot process?
Replies
1
Views
1K
Max Work From Heat Engine Reservoirs
Replies
11
Views
2K

Hot Threads

Recent Insights

Back
Top