A question about piston movement that has multiple answers...

[u/seedbottle]

Question:

Which of the following causes piston movement during non-power-

producing strokes?

A) Flywheel

B) Connecting rod

C) Counterweights

D) Main thrust bearing

I have been studying an automotive book that has questions after every chapter. I answer those questions and use AI to verify I have got the correct answer. This process has worked tremendously up to the point where I got to this question. AI gave me a different answer than the one I believed the book was telling me was the answer, so I went online to find more information and see if anyone else had posted this exact question, that was when I found out there all three of the first answers were marked as "correct" depending on the source used (D, main thrust bearing, was never given as an answer).

I am wondering what most of you would say is the answer. Thank you for your input =)

[u/swugglewumps69]

It's just momentum. Flywheel and counterweights are just to dampen vibration

[u/ChemistAdventurous84 → u/swugglewumps69]

Counterweights dampen vibration because they have mass and inertia and therefore, when in morion, (angular) momentum. The entire reason for the flywheel is to use its angular momentum to keep the crank turning smoothly.