# Physics

posted by .

Some Carnot engine has an efficiency 0.700. The hot reservoir temperature is 900K. This means that the temperature of the cold reservoir is 270K. If the cold reservoir is dropped to 260K, the new efficiency is 0.701.

If the output of the power is kept constant by increasing the amount of time it takes to complete a cycle, what's the ratio of the wasted transfer of heat after the change to before the change?

• Physics -

In your first paragraph, the efficiency of a Carnot engine would be 0.711 with a 260 cold reservoir, not 0.701.

Your second paragraph does not make sense to me. Increasing the time it takes to make a cycle will not increase the power.

The ratio of wasted heat with 260 cold reservoir to that with 270 cold reservoir is (1-.711)/(1-0.700) = 289/300 = 96%

• Physics -

That didn't work. I think you're supposed to find work in each case but I'm not sure how to do that.

• Physics -

Oh wait never mind. Seems like there's some rounding issues going on with the online system. Thanks for the help drwls.

## Similar Questions

1. ### help physcis

At what cold-reservoir temperature (in degree C) would a Carnot engine with a hot-reservoir temperature of 350degree C have an efficiency of 70%?
2. ### Physics

In one cycle a heat engine absorbs 530 J from a high-temperature reservoir and expels 310 J to a low-temperature reservoir. If the efficiency of this engine is 55% of the efficiency of a Carnot engine, what is the ratio of the low …
3. ### Physics

In one cycle a heat engine absorbs 450 J from a high-temperature reservoir and expels 290 J to a low-temperature reservoir. If the efficiency of this engine is 57% of the efficiency of a Carnot engine, what is the ratio of the low …
4. ### physics

A heat engine has a hot reservoir of 680°C and a cold reservoir of 220°C. What is the efficiency of the engine?
5. ### physics

The hot reservoir for a Carnot engine has a temperature of 926 K, while the cold reservoir has a temperature of 441 K. The heat input for this engine is 3730 J. The 441-K reservoir also serves as the hot reservoir for a second Carnot …

Converting sunlight to electricity with solar cells has an efficiency of 15%. It's possible to achieve a higher efficiency (though currently at higher cost) by using concentrated sunlight as the hot reservoir of a heat engine. Each …
7. ### Physics

A heat engine has a hot reservoir of 680°C and a cold reservoir of 220°C. What is the efficiency of the engine?
8. ### physics

A heat engine has a hot reservoir of 680°C and a cold reservoir of 220°C. What is the efficiency of the engine?
9. ### Physics

A 20% efficient real engine is used to speed up a train from rest to 7.0 m/s. An ideal (Carnot) engine using the same cold and hot reservoir would accelerate the same train from rest to a speed of 8.0 m/s using the same amount of fuel. …
10. ### Physics

A heat engine operating between a cold reservoir temperature of 300K and a hot reservoir takes 200J of heat from the hot reservoir and delivers 120J of heat to the cold reservoir in a cycle. The minimum temperature of the hot reservoir …

More Similar Questions