Final answer:
The efficiency of the cyclical heat engine is 5.86%.
Step-by-step explanation:
To find the efficiency of the cyclical heat engine, we can use the formula:
Efficiency = (Useful work output / Heat input)
Given that the heat transfer into the engine is 2.56 × 10⁶ J and the work done by the engine is 1.50 × 10⁵ J, we can plug in these values into the formula:
Efficiency = (1.50 × 10⁵ J / 2.56 × 10⁶ J)
Efficiency ≈ 0.0586 or 5.86%
The efficiency of the cyclical heat engine is 5.86%.