Finding friction and tension for a train

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SUMMARY

The discussion focuses on calculating the friction present in a passenger car of a UTA Trax train and the tension in the cable connecting the locomotive to the passenger car. The locomotive applies a force of 96050 Newtons, with a mass of 1750 kg, while the passenger car has a mass of 949 kg. The acceleration of the train is given as 1.29 m/s². Participants clarify that the friction force (Ff) is not simply derived from ΣF=Ff=ma, as it involves additional factors like rolling resistance and bearing friction.

PREREQUISITES
  • Understanding of Newton's Second Law (F=ma)
  • Basic concepts of friction and tension in physics
  • Knowledge of forces acting on connected systems
  • Familiarity with rolling resistance and bearing friction
NEXT STEPS
  • Calculate friction forces in connected systems using advanced physics principles
  • Explore the concept of rolling resistance in vehicles
  • Learn about tension in cables and its relation to connected masses
  • Review examples of force analysis in multi-body systems
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Students in AP Physics, educators teaching mechanics, and anyone interested in understanding the dynamics of connected systems in motion.

aftonmathews
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Homework Statement


A UTA Trax train engine can apply 96050 Newtons and locomotive has a mass of 1750 kg. The passenger car has a mass of 949 kg.
(A) If the train accelerates at a rate of 1.29 m/s/s, how much friction is present in the passenger car? (Assume the locomotive moves without slipping and assume air resistance is negligible.)
(B) Assuming the engine and passenger car are connected with a cable, what is the tension in the cable connecting the engine to the passenger car?

Homework Equations


I tried using (ΣF=Ff=ma) but after working it out and submitting my answer, I got it wrong. Also, for tension, I couldn't even find an equation to solve for tension.

The Attempt at a Solution


I've worked the question over and over again but I can't find a correct answer. I'm in AP Physics and can't move onto the next unit without understanding friction and tension. Thank you for helping!
 
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aftonmathews said:
I tried using (ΣF=Ff=ma) but after working it out and submitting my answer, I got it wrong.

Please show us one of your attempts so we can see where you are going wrong.

Typically Ff=ma would give you the friction force that effectively pulls the train along. However that's not what they ask you to calculate.

They ask for the friction in the passenger car. I believe they mean the total of things like rolling resistance and friction in bearings (eg the force holding it back).
 
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