Internal-Combustion Engine Prototypes Ranking Task?

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SUMMARY

The forum discussion centers on ranking internal combustion engines based on their designed power output and thermal efficiency. The engines are evaluated using the equations P=Work/t and Work=Qin-Qout, where Qin and Qout represent the energy input and output, respectively. The calculated power outputs for the engines are as follows: P1 > P6 > P3 > P5 > P4 > P2. The thermal efficiency is defined by the formula 1 - (Qin/Qout), which is essential for the next phase of the ranking task. The user expresses confusion over discrepancies with the results provided by the Mastering Physics platform.

PREREQUISITES
  • Understanding of thermodynamics principles, specifically energy input and output.
  • Familiarity with the equations for power output and thermal efficiency.
  • Knowledge of frequency and its relation to time in calculations.
  • Basic proficiency in using physics simulation tools like Mastering Physics.
NEXT STEPS
  • Review the calculation of power output using the formulas P=Work/t and Work=Qin-Qout.
  • Study the concept of thermal efficiency and its calculation using 1 - (Qin/Qout).
  • Explore common pitfalls in thermodynamic calculations in educational platforms like Mastering Physics.
  • Practice ranking engines based on both power output and thermal efficiency with additional examples.
USEFUL FOR

Students studying thermodynamics, physics educators, and anyone involved in the analysis of internal combustion engine performance and efficiency metrics.

cupcake
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Homework Statement




Rank these engines on the basis of their designed power output and their thermal efficiency.

1) Qin = 3000 J, Qout = 1500 J, f=150 Hz.
2) Qin = 4000 J, Qout = 3000 J, f=50 Hz.
3) Qin = 1000 J, Qout = 200 J, f=200 Hz.
4) Qin = 2000 J, Qout = 500 J, f=50 Hz.
5) Qin = 2000 J, Qout = 1000 J, f=100 Hz.
6) Qin = 1500 J, Qout = 500 J, f=200 Hz.

Homework Equations



P=Work/t, and Work=Qin-Qout

The Attempt at a Solution



I calculated the power output using the above formulas, where t=1/f, but I don't know why my answers are wrong... this is mastering physics question :(
 
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cupcake said:

Homework Statement




Rank these engines on the basis of their designed power output and their thermal efficiency.

1) Qin = 3000 J, Qout = 1500 J, f=150 Hz.
2) Qin = 4000 J, Qout = 3000 J, f=50 Hz.
3) Qin = 1000 J, Qout = 200 J, f=200 Hz.
4) Qin = 2000 J, Qout = 500 J, f=50 Hz.
5) Qin = 2000 J, Qout = 1000 J, f=100 Hz.
6) Qin = 1500 J, Qout = 500 J, f=200 Hz.

Homework Equations



P=Work/t, and Work=Qin-Qout

The Attempt at a Solution



I calculated the power output using the above formulas, where t=1/f, but I don't know why my answers are wrong... this is mastering physics question :(
Perhaps you could show us your answers. What is your equation for thermal efficiency? Are you taking that into account?

AM
 
so,

1) W1=1500 P1=W1/t= 225000
2) W2=1000 P2=W2/t= 50000
3) W3=800 P3=W3/t= 160000
4) W4=1500 P4= 75000
5) W5=1000 P5=100000
5) W6=1000 P6=200000

so, the rank from the largest to the smaller will be, P1 > P6 > P3 > P5 > P4 > P2

thermal efficiency formula is 1-Qin/Qout, that one is for the next question (arrange by basis of thermal efficiency)
 
cupcake said:
so,

1) W1=1500 P1=W1/t= 225000
2) W2=1000 P2=W2/t= 50000
3) W3=800 P3=W3/t= 160000
4) W4=1500 P4= 75000
5) W5=1000 P5=100000
5) W6=1000 P6=200000

so, the rank from the largest to the smaller will be, P1 > P6 > P3 > P5 > P4 > P2

thermal efficiency formula is 1-Qin/Qout, that one is for the next question (arrange by basis of thermal efficiency)
Looks right. What is the problem?

AM
 
Andrew Mason said:
Looks right. What is the problem?

AM

I don't know..masteringphysics said it's wrong :(
 

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