Internal-Combustion Engine Prototypes Ranking Task?

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The discussion focuses on ranking internal combustion engines based on their designed power output and thermal efficiency. Users calculated power output using the formula P=Work/t, where Work is derived from Qin-Qout, but encountered discrepancies with their results. The thermal efficiency formula discussed is 1-Qout/Qin, which is intended for a subsequent ranking task. Despite calculations appearing correct, the original poster received incorrect feedback from the mastering physics platform. The conversation highlights the challenges of accurately applying formulas in physics homework.
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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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