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A turning moment diagram is a graph showing the variation of torque produced by an engine or motor with the angle of rotation of the output shaft - AQA - A-Level Physics - Question 2 - 2019 - Paper 6
Question 2
A turning moment diagram is a graph showing the variation of torque produced by an engine or motor with the angle of rotation of the output shaft. Figure 2 shows th... show full transcript
Worked Solution & Example Answer:A turning moment diagram is a graph showing the variation of torque produced by an engine or motor with the angle of rotation of the output shaft - AQA - A-Level Physics - Question 2 - 2019 - Paper 6
Step 1
State what is represented by the area between the curve and the angle axis for a turning moment diagram.
Answer
The area between the curve and the angle axis in a turning moment diagram represents the work done by the engine or motor over one complete cycle of operation. This work done can be interpreted as the energy produced by the engine, which is necessary for driving machinery.
Step 2
Discuss why, to drive this machine, the diesel engine would need to be fitted with a flywheel.
Answer
To effectively drive a machine with a low moment of inertia, the diesel engine must be fitted with a flywheel for several reasons:
Why the Electric Motor Does Not Require a Flywheel
Electric motors typically provide a smooth torque output and operate at a constant speed. Therefore, the variability in torque is minimal, and the motor can continuously drive the load without significant fluctuations.
Why the Torque of the Diesel Engine Varies Over One Cycle
The torque of a diesel engine varies due to its operational cycles, including induction, compression, power, and exhaust strokes. At certain points in the cycle—specifically during induction and exhaust—the torque can drop to zero, resulting from the engine's design and operational phases.
How the Moment of Inertia of the Flywheel Influences the Motion of the Output Shaft
The moment of inertia of the flywheel serves to smooth out the torque output by the engine. By storing rotational energy, the flywheel helps maintain a consistent speed and compensates for the variations in torque throughout the engine cycle, ensuring that the output shaft maintains a steady motion even during the low-torque phases of operation.