Do A and C have same or different KE at the end?

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Homework Help Overview

The discussion revolves around the kinetic energy (KE) of two blocks, A and C, at the end of their motion on a frictionless ramp. The original poster is exploring the implications of conservation of energy, specifically whether both blocks can have the same final KE despite differing horizontal distances traveled.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster questions the validity of the assumption that blocks A and C can have the same final KE, given their equal initial potential energy (mgh) but different horizontal distances. Some participants discuss the implications of the answer template and whether it allows for both blocks to be treated equivalently in terms of KE.

Discussion Status

Participants are engaging in a back-and-forth about the assumptions underlying the problem. Some guidance has been offered regarding the interpretation of the answer template, suggesting that the order of A and C may not matter. However, there is no explicit consensus on the interpretation of the energy conservation principle in this context.

Contextual Notes

There is mention of an answer template that may impose restrictions on how the blocks' KE can be represented, leading to confusion about whether they can be considered equal. The discussion is also influenced by the context of a homework assignment, which may impose specific rules on how answers should be formatted.

JessicaHelena
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Homework Statement



Please look at the attached screenshot.

Homework Equations



Assuming the ramp is frictionless, Ei = Ef and thus mgh = KE ( = 1/2mv^2, which isn't really necessary here)

The Attempt at a Solution


I'm okay with all other examples except for A and C. From the answer template given, I don't think I'm allowed to let two different blocks have the same final KE, but even though C travels a shorter horizontal distance, the conservation of energy tells me they should have the same KE at the end (bc their mgh is the same)! Am I missing something here?
 

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You are correct and the answer template is a bit misleading. Conclusion: A and C can be entered in the order of your choice. Or in one box if the work is judged by a human instead of a counting machine.
 
JessicaHelena said:
I'm okay with all other examples except for A and C. From the answer template given, I don't think I'm allowed to let two different blocks have the same final KE, but even though C travels a shorter horizontal distance, the conservation of energy tells me they should have the same KE at the end (bc their mgh is the same)! Am I missing something here?

I don't think so - since there are no losses - the final KE should be same as initial PE - mgh as you indicated. I guess in the template it wouldn't matter if you rank AC or CA in either order.
 
Alright, I'll put it that way then. Thank you!
 

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