Mechanical Energy: Kinetic & Potential Energy Balance

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Homework Help Overview

The discussion revolves around the concept of mechanical energy, specifically the relationship between kinetic energy and gravitational potential energy in a system. Participants are examining a multiple-choice question regarding the nature of total mechanical energy and its distribution between these two forms of energy.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning whether kinetic energy can be equal to potential energy at all times and are reflecting on their previous experiences with projectile motion to evaluate this claim. There is an exploration of the implications of counterexamples in disproving propositions.

Discussion Status

The discussion is active, with participants engaging in a back-and-forth regarding the validity of different answer choices based on their understanding of energy conservation principles. Some guidance is offered to reflect on past problems, emphasizing logical reasoning over direct answers.

Contextual Notes

Participants are encouraged to consider their previous experiences with energy problems, indicating a reliance on personal understanding and examples to inform their reasoning. There is an implicit expectation to analyze the question critically rather than seeking definitive answers.

wolves5
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1. The total mechanical energy of a system:

a. is split equally between kinetic energy and gravitational potential energy.
b. is constant as long as only conservative forces act on it.
c. is either only kinetic energy or only gravitational potential energy at any given time.
d. cannot be determined for most naturally occurring systems.

For this question, I think the answer is A. This is because Total Mechanical Energy is eqaul to Potential Energy + Kinetic Energy. Is my reasoning right?
 
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So, you're proposing that KE is always equal to PE?
 
Yes..isnt that right?
 
In all the projectile problems that you've worked on, was potential energy always (at all times) equal to kinetic energy? Even, for example, when a vertically launched projectile is at the top of its trajectory?
 
Oh no it wasnt the same. So since its not split equally, it would be C then?
 
wolves5 said:
Oh no it wasnt the same. So since its not split equally, it would be C then?

I think that you should reflect on the problems that you've done involving PE and KE and try to draw logical arguments for accepting or rejecting the provided choices. Remember, a single counterexample disproves a proposition.

I'm not going to answer your question for you by eliminating or confirming them one at a time when you say something like, "Is it C?" :smile:
 

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