Internal-Combustion Engine Prototypes Ranking Task?

[cupcake]

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 :(

 

[Andrew Mason]

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

 

[cupcake]

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)

 

[Andrew Mason]

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

 

[cupcake]

Looks right. What is the problem?

AM

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