Can acceleration be relevant of third derivative?

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Acceleration is indeed relevant to the third derivative of position, known as "jerk," which describes changes in acceleration. Jerk occurs in systems with non-constant acceleration, indicating that any change in acceleration results in jerk. In Newtonian mechanics, there are no inherent limits to jerk, unlike velocity and acceleration, which cannot be infinite for massive objects. This means jerk can theoretically be modeled as infinite under certain conditions, such as when a constant force is suddenly applied. The discussion highlights the conceptual flexibility of jerk in physics, despite its practical implications.
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can acceleration be relevant of third derivative? something like m\ddot{x}=k\dddot{x}
 
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The third time-derivative of position, which is also the first time-derivative of acceleration, is often called "jerk." Anytime you have a system that does not have constant acceleration, you have jerk. Anytime the acceleration changes, you have jerk. So the simple answer to your question, is yes.

But there are no limits to jerk in Newtonian mechanics. Infinite velocity doesn't make much sense, and you can't have infinite acceleration of a massive object because that would imply infinite force. But there are no such restrictions for jerk. Jerk can be modeled as infinite, such as when a non-zero constant force/acceleration is initially applied to an object. (Now whether jerk is actually ever truly infinite in nature, I'll leave that for you to think about. But it certainly can be modeled that way in Newtonian mechanics -- that's my point.)
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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