Question regarding distance traveled up an incline?

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Homework Help Overview

The problem involves a bobsled that has partially slowed down on an incline and needs to be brought to a stop. The incline is at a 30-degree angle with a coefficient of kinetic friction of 0.60, and the sled enters the incline at a speed of 25.0 m/s. The participants are discussing how to calculate the distance traveled along the incline before stopping.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to use an energy approach but is unsure how to incorporate the angle of the incline. They propose a formula but express uncertainty about its correctness. Other participants suggest considering gravitational potential energy and question how to incorporate it into the calculations. There is also a discussion about deriving a formula tailored to the specific problem rather than relying on existing formulas.

Discussion Status

The discussion is active, with participants exploring different aspects of energy conservation and the role of gravitational potential energy. Some guidance has been offered regarding the importance of understanding the underlying concepts before applying formulas. There is no explicit consensus yet, as multiple interpretations and approaches are being considered.

Contextual Notes

Participants are navigating the complexities of energy conservation in the context of inclined motion and friction, with some expressing confusion about the definitions and calculations involved. The original poster's uncertainty about their initial approach indicates a need for clarification on the principles at play.

choyphin
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Homework Statement


After a bobsled race, the sled and riders have been partially slowed down up in an icy incline, but they need to be brought to a stop. This happens on a portion of track inclined at 30 degrees that has a coefficient of kinetic friction of 0.60. The sled enters the incline at 25.0 m/s. How far does it travel along the incline before stopping?

Homework Equations


(1/2)mv(final)^2 - (1/2)mv(initial)^2 = Ffriction

The Attempt at a Solution


Im not sure how to incorporate the angle of the incline, but as an attempt, i did
1/2vi^2=FG(cos 30) d
and i got 88.3 m. I'm not sure if that's right...
 
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Looks like you're using an energy approach. Good. But don't forget gravitational PE, which increases as the sled goes up the incline.
 
How would you incorporate gravitational PE? and also, would the formula
d = vi^2 / [2g(sin30 + ucos30)] work?
 
choyphin said:
How would you incorporate gravitational PE?
What's the definition of gravitational PE? How do you calculate it?
and also, would the formula
d = vi^2 / [2g(sin30 + ucos30)] work?
I would advise against looking for a formula to plug into unless you fully understand what the formula means. Better to stick with the basics and derive your own formula, tailor-made to the specific problem. (That formula is close, but not quite right, anyway.)

The basic idea that you want to use is energy conservation:
Energy(initial) + Work done by friction(which is negative) = Energy(final)

Here "Energy" means total mechanical energy: KE + PE.
 

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