# Machine Dynamics Questions and Answers – Turning Moment Diagram for a Single Cylinder Double Acting Steam Engine

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This set of Machine Dynamics Objective Questions & Answers focuses on “Turning Moment Diagram for a Single Cylinder Double Acting Steam Engine”.

1. In the figure given below, the quantity represented by the arrow is known as ___________ a) Maximum Torque
b) Minimum Torque
c) Maximum Force
d) Mean resisting torque

Explanation: In a turning moment diagram given above, the line pointed out by the arrow is the value of mean torque and hence it is called mean resisting torque.

2. Turning moment is maximum when the crank angle is 90 degrees.
a) True
b) False

Explanation: Referring the turning moment diagram for a single cylinder double acting steam engine, the minimum values occur at 0, 180 and 360 degrees and maximum values occur at 90 and 270 degrees.

3. The curve abc in figure below is known as _________ a) Instroke
b) Outstroke
c) Positive couple
d) Negative couple

Explanation: In the given figure, the curve during the curve abc there is an ascent in the motion. The ascent of motion is known as outstroke thus curve abc is called outstroke.

4. The curve cde in figure below is known as _________ a) Instroke
b) Outstroke
c) Positive couple
d) Negative couple

Explanation: In the given figure, the curve during the curve cde there is a descent in the motion. The descent of motion is known as intstroke, thus curve cde is called instroke.

5. When engine torque is more than mean resisting torque, then the flywheel _______
a) Has uniform velocity
b) Has 0 velocity
c) Has acceleration
d) Has retardation

Explanation: When the difference between T-Tmean is positive the work is done by the steam and the crankshaft accelerated which results in acceleration of flywheel.

6. When engine torque is less than mean resisting torque, then the flywheel _______
a) Has uniform velocity
b) Has 0 velocity
c) Has acceleration
d) Has retardation

Explanation: When the difference between T-Tmean is negative the work is done on the steam and the crankshaft decelerates which results in retardation of flywheel.

7. Area of the turning moment diagram represents _______
a) Work done
b) Work done per revolution
c) Power generated
d) Power generated per revolution

Explanation: Since the work done is the product of the turning moment and the angle turned, therefore the area of the turning moment diagram represents the work done per revolution.

8. In actual practice, engine is assumed to work against the mean resisting torque.
a) True
b) False

Explanation: In actual practice, the engine is assumed to work against the mean resisting torque, therefore the area under the curve gives the work done against the mean resisting torque.

Sanfoundry Global Education & Learning Series – Machine Dynamics. 