Solving Slider Crank Problem: Tips & Advice

AI Thread Summary
The discussion focuses on solving a slider crank problem involving angular velocity and its impact on acceleration and velocity graphs. Participants suggest that while the exact value of angular velocity (omega) may be unknown, it can be assumed as a constant for calculations. This assumption allows for the determination of theta at maximum velocity and minimum acceleration without affecting the overall shape of the graphs. The conversation emphasizes using piston motion equations as a resource for deriving the necessary results. Overall, the key takeaway is that assuming a constant angular velocity simplifies the problem-solving process.
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I'm having trouble figuring out this problem. I know how to solve the problem if the angular velocity was known but there seem to be too many unknowns to be able to generate graphs. If anyone can offer advice that would be great.
 

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If you know how to solve the problem, you should have an equation for acceleration as a function of theta (you may not know the value of omega, but you know that the angular velocity is a constant). There's no reason you can't plot this function if you scale your y-axis in units of omega^2...
 
I'm having trouble figuring this out when I put the y components together the theta gets canceled out and velocity is not linear in this problem and I have no idea where my mistake was
 
The problem is basically asking you to find two things:

  • Theta at max velocity
  • Theta at min acceleration
To find these two values, you can just assume a value for omega (angular speed, d/dt of theta) because those values of theta will not change with angular speed. The graphs of velocity and acceleration vs. theta will change in magnitude but not in shape, so I would just assume soemthing for omega that makes calculation easy (like 60 rpm, 2pi rad/s). The problem states that you should assume the angular velocity is constant, which tells me you are meant to assume a constant value for it.

The piston motion equations should help you find the result:
http://en.wikipedia.org/wiki/Piston_motion_equations
 
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