Calculating Distance for a Train on a 1% Grade

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Homework Help Overview

The discussion revolves around a physics problem involving a train moving up a 1% grade, with specific parameters including mass, friction force, and initial and final speeds. The objective is to determine the horizontal distance traveled before the train's speed decreases from 12 m/s to 9 m/s.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the use of kinematic equations to relate velocity and acceleration, while questioning how to determine acceleration given the forces acting on the train. There is also a focus on understanding the relationship between the calculated distance and the horizontal distance traveled.

Discussion Status

Some participants have provided guidance on using kinematic equations, while others are exploring the implications of the train coasting without engine power. The conversation reflects a mix of attempts to clarify the problem setup and the necessary calculations, with no clear consensus reached yet.

Contextual Notes

Participants note the importance of understanding the forces acting on the train, including friction, and the implications of the train's motion on the calculation of acceleration. There is a request for the original poster to demonstrate their own efforts in solving the problem.

A_Sushi
Can anyone help with the following question, please?
1.
A 60,000kg train is being pulled up a 1 percent grade (it rises 1m for each horizontal 100m). The friction force opposing the motion of the train is 4,000N. Initial speed of the train is 12 m/s. Through what horizontal distance will the train move before its speed is reduced to 9m/s?
3.
The answer suppose to be 191.2 m. I got 472.5 m as follows:
Fd=m*(v2-v2)/(2*distance)
4 000 = (60 000*(92-122)) / (2*distance) = 472.5 m
 
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Use the kinematic equation:

##\Delta x=\dfrac{v_f^2-v_i^2}{2a}##

You are given the initial and final velocities...what is the acceleration? How does ##\Delta x## relate to the horizontal distance?
 
@A_Sushi Please do not delete our template, but use it instead. It is important for many reasons. Also we request you to show us some effort on your own, to see how we could help you best. Different people might have different difficulties. Thank you.
 
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MarkFL said:
Use the kinematic equation:

##\Delta x=\dfrac{v_f^2-v_i^2}{2a}##

You are given the initial and final velocities...what is the acceleration? How does ##\Delta x## relate to the horizontal distance?
The acceleration is not given. I do not know how to calculate the acceleration
 
A_Sushi said:
how to calculate the acceleration
Even though it says the train is being pulled up, I think you have to assume there is no engine attached, it is just coasting.
What are the forces on the train? What equation can you write relating those to acceleration?
 

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