How to find the temperature of the cold reservoir?

[PhysicsstudentNOR]

Homework Statement

Carnot engine A has an efficiency of 0.60, and Carnot engine B has an efficiency of 0.80. Both engines utilize the same hot reservoir, which has a temperature of 650 K and delivers 1200 J of heat to each
engine. Find the magnitude of the work produced by each engine and the temperatures of the cold reservoirs that they use.

Homework Equations

The equation I used: e(carnot)=1-Tc/Th

The Attempt at a Solution

Tc=1-e(carnot)*Th
Tc= 1-0,60*650
Tc= -389 K

 

[DrClaude]

The equation I used: e(carnot)=1-Tc/Th

The Attempt at a Solution

Tc=1-e(carnot)*Th

You didn't isolate Tc correctly.

 

[PhysicsstudentNOR]

You didn't isolate Tc correctly.

What's the right way to do it?

 

[DrClaude]

The equation
$$
e = 1 - \frac{T_c}{T_h}
$$
is correct, but that doesn't mean that
$$
T_c = 1 - e T_h
$$
Start by moving the 1 to the same side as $e$.

 

[PhysicsstudentNOR]

The equation
$$
e = 1 - \frac{T_c}{T_h}
$$
is correct, but that doesn't mean that
$$
T_c = 1 - e T_h
$$
Start by moving the 1 to the same side as $e$.

Okey, tnx