Speeds of the rolling ball at different points in this roller coaster track

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Homework Help Overview

The discussion revolves around the speeds of a rolling ball at different points on a roller coaster track, specifically analyzing the relationship between gravitational potential energy and kinetic energy. Participants are exploring how the ball's speed changes at various elevations on the track.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the reasoning behind the speed rankings of points A, B, C, and D on the track, particularly the assertion that A is the slowest despite being at a lower elevation. They are exploring the effects of elevation changes on speed and energy conservation principles.

Discussion Status

The discussion is active, with participants raising questions about gravitational potential energy and its impact on speed. Some are seeking clarification on the implications of moving up versus down on the track, while others are considering the problem's constraints regarding friction and initial conditions.

Contextual Notes

Some participants note that they are working within specific educational constraints, such as not having covered gravitational potential energy in their studies yet. The problem is also framed to be considered without the effects of friction or air resistance.

Ineedhelpwithphysics
Messages
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Homework Statement
The image is below.
Relevant Equations
Distance/time
Physics.png

For this question i tried to reason with my self that C was the fastest and A was the second fastest. B would be the third fastest and D would be the least fastest since the ball has to go up. I looked up the answer and it says that C is the fastest , B and D are equal, and A is the slowest. How is that possible if A is the slowest even though with D you have to go up. And any time you go up you lose speed.
Thank you for helping.
 
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Ineedhelpwithphysics said:
And any time you go up you lose speed.
What happens to your speed when you go down ?
What happens to your speed when you're on the same level ?
 
Ineedhelpwithphysics said:
Homework Statement:: The image is below.
Relevant Equations:: Distance/time

I looked up the answer and it says that C is the fastest , B and D are equal, and A is the slowest.
What are the gravitational potential energies (GPEs) at those points on the track, compared to each other? Remember that KE+PE should be constant unless there are losses (like air resistance).
 
hmmm27 said:
What happens to your speed when you go down ?
What happens to your speed when you're on the same level ?
Yes exactly so how is A the slowest if the ball is going down.
 
berkeman said:
What are the gravitational potential energies (GPEs) at those points on the track, compared to each other? Remember that KE+PE should be constant unless there are losses (like air resistance).
I didn't learn gravitational potential energies I am in chapter 3 of paul hewitts conceptual physics book.
 
Ineedhelpwithphysics said:
hmmm27 said:
Ineedhelpwithphysics said:
any time you go up you lose speed.
What happens to your speed when you go down ?
What happens to your speed when you're on the same level ?
Yes exactly so how is A the slowest if the ball is going down.
"Yes exactly" to what ? exactly.

The problem says "released", not "shoved", "pushed" or "shot". At point "O" its speed is zero. Do things slow down the farther they fall ?

Also, the problem is meant to be envisioned/answered without consideration for friction forces ; the ball's speed isn't being affected by the air and it's not rubbing against the track.
 
Last edited:
Ineedhelpwithphysics said:
Yes exactly so how is A the slowest if the ball is going down.
Going down means it is getting faster, not that it is already fast. And it can't be at the highest speed yet if it is still accelerating.
 

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