Difficulty: Easy
Correct Answer: Yes
Explanation:
Introduction / Context:
Steam engines may be single-acting (steam acts on one side of the piston only) or double-acting (steam acts alternately on both sides). The turning-moment uniformity and power output differ between these arrangements. This item checks the basic kinematics and work delivery per revolution for a double-acting engine.
Given Data / Assumptions:
Concept / Approach:
In a double-acting engine every stroke is a power (working) stroke because steam pressure pushes the piston during both the outstroke and the instroke. Therefore, for each revolution of the crankshaft—corresponding to one back-and-forth piston motion—there are two working strokes, one in each direction.
Step-by-Step Solution:
Relate kinematics: one crank revolution ↔ one full piston cycle (to-and-fro).Recognize valve timing: steam admitted to one side while the other side exhausts, then roles reverse.Note work delivery: both strokes produce positive work on the crank.Conclude: two working strokes per revolution in a double-acting engine.
Verification / Alternative check:
Indicator diagrams for both ends of the cylinder show positive loop areas for each stroke, confirming two power events per revolution.
Why Other Options Are Wrong:
“No” and variations assume idle strokes like many I.C. engines; steam engine valving makes both strokes productive.
“Only with two cylinders” is incorrect; it holds with a single double-acting cylinder.
Common Pitfalls:
Projecting four-stroke internal combustion logic onto steam engines; forgetting that external steam supply enables power on both strokes.
Final Answer:
Yes
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