F=ma applied to slider crank piston motion

AI Thread Summary
The discussion focuses on applying Newton's second law, F=ma, to analyze the forces acting on a piston in a slider crank mechanism. The user seeks to determine the necessary force to maintain piston motion, particularly during acceleration and deceleration phases. They reference a diagram that includes combustion force, inertial force, and resultant force, indicating a need to understand the forces at play between 650 to 90 degrees of the cycle. The inquiry highlights the complexity of force requirements at different points in the piston's motion. Understanding these dynamics is crucial for optimizing performance in mechanical systems.
Kalus
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I'm struggling to apply F=ma to the motion of a slider crank, more specifically the piston. I want to find out how much force is nessesary to keep the piston in motion. Essentially, in the mechanism there is acceleration and deceleration, does that mean only at some points in the cycle there is force needed to move the piston?

Using the equations derived for the motion of a piston:

http://upload.wikimedia.org/wikipedia/en/math/1/6/8/1686ee2f8b1d67ce1eb1aa4fb4b0daac.png

9b2e87b937f4942da5b81113ade86f0e.png


29bde840b3d4c0a03708f2d941f33a54.png


Gives you this:

800px-Graph_of_Piston_Motion.png
 
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Sorry, I should add why I'm asking this. I have the following diagram:

0klgQ.jpg


Where f_g is the combustion force, f_j is the inertial force and f is the resultant force. I'm trying to work out what's providing the force to overcome the acceleration around 650 to 90 degrees.
 
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