Ball falling on to parabolic track

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Homework Help Overview

The problem involves a 50 g ball released from rest on a track that includes both a straight segment inclined at 30 degrees and a parabolic segment defined by the equation y = 1/4x^2. The original poster is attempting to determine the final height of the ball after it rolls down and back up the track.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster discusses energy conservation principles, including kinetic and potential energy, and expresses uncertainty about how to apply the parabolic equation to find the final height. Some participants question the clarity of the problem statement and the assumptions regarding potential energy at different heights. Others explore the implications of the inclined plane on gravitational effects.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem. Some guidance has been offered regarding the relationship between potential energy and height, but there is no explicit consensus on the approach to take or the final outcome.

Contextual Notes

Participants note potential confusion regarding the effects of the inclined plane on gravitational force and the implications of the parabolic shape on the final height of the ball. The original poster also mentions a lack of clarity in the problem statement.

jemstone
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1. A 50 g ball is released from rest 1.0 m above the bottom of the track. It rolls down a straight 30 degree segment, then back up a parabolic segment whose shape is given by y = 1/4x^2, where x and y are in m.

There is a picture shown too, but I can't figure out how to get it in the post. I figure that enough information is given to understand the problem.

2. KE = 1/2 mv^2
PE = mgy
KEf + Ugf = Ki + Ugi

3. I really don't know what I'm doing, but we know that:
m=.50 kg
yi = 1
xf = 1 / (tan30) = 1.73
I think the question is asking me to find the final y which I could find from the equation of the parabola, but then I need x. I'm just really lost.
 
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You weren't too clear on what the question states, so I'll just mention that the potential energy is the same for any x, if we have the same y. Also, when a ball rolls to the top of a hill or something, its kinetic energy must be zero because, for a brief moment, it isn't moving.
 


I think I'm having a hard time approaching this problem. I know that I'm looking for the final y value.

I also am thinking that since this has an inclined plane, the gravity isn't going to be g, but gsin30 (but it's possible that I am making this more complicated than it is).

So maybe we use:
(1/2)mvf2 + mgsin30yf = (1/2)mvi2 + mgsin30yi
0 + (.05 kg)(9.8)(sin30)yf = 0 + (.05 kg)(9.8)(sin30)(1m)
.245yf = .245
yf = 1

So that means that I'm not using the parabolic equation and the final height is the same as the initial height? Does this make sense?
 


Ok I think I figured it out. I made it harder than it should be. Regardless of the shape of the trajectory, the object will go to the same height, 1m.
 

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