A heat engine receives 7.0 x 10^3 J of heat and loses 3.0 x 10^3 J in each cycle. What is the efficiency?
1-30%
2-43%
3-57%
4-70%
5-100%
Eff. = Eo/Ei = (7000-3000)/7000 = 0.57 =
57%
To find the efficiency of a heat engine, you can use the formula:
Efficiency = (Useful Work Output / Heat Input) * 100%
In this case, the Useful Work Output refers to the amount of heat that the heat engine converts into useful work, while the Heat Input refers to the total amount of heat that the heat engine receives.
Given:
Heat Input = 7.0 x 10^3 J
Useful Work Output = Heat Input - Heat Lost = 7.0 x 10^3 J - 3.0 x 10^3 J = 4.0 x 10^3 J
Now, we can substitute these values into the efficiency formula:
Efficiency = (4.0 x 10^3 J / 7.0 x 10^3 J) * 100%
Simplifying the expression:
Efficiency = (0.5714) * 100%
Efficiency ≈ 57%
Therefore, the correct answer is option 3 - 57%.
The efficiency of a heat engine can be calculated using the formula:
Efficiency = (Work output / Heat input) x 100%
Work output is the difference between the heat input and the heat lost:
Work output = Heat input - Heat lost
Given:
Heat input = 7.0 x 10^3 J
Heat lost = 3.0 x 10^3 J
Substituting these values into the formula:
Work output = (7.0 x 10^3 J) - (3.0 x 10^3 J)
= 4.0 x 10^3 J
Efficiency = (4.0 x 10^3 J / 7.0 x 10^3 J) x 100%
Simplifying this expression:
Efficiency = 0.5714 x 100%
= 57.14%
Therefore, the efficiency of the heat engine is approximately 57%, which corresponds to option 3