Simple coefficient of friction problem

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Homework Help Overview

The discussion revolves around a physics problem involving the coefficient of friction, specifically focusing on a car sliding on wet concrete. The original poster questions the validity of the problem setup, particularly regarding the forces acting on the car and its motion at a constant speed.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to reconcile the given forces with the motion of the car, expressing confusion about the adequacy of the applied force to maintain sliding at a constant speed. Some participants question the assumptions about static versus kinetic friction and the implications of the car being in motion.

Discussion Status

Participants are actively engaging with the problem, with some providing clarifications regarding the conditions of motion and the definitions of friction types. There is an ongoing exploration of the implications of the problem's parameters without reaching a consensus.

Contextual Notes

The problem includes specific coefficients of friction provided in the context, which are being discussed in relation to the scenario presented. There is an emphasis on understanding the equilibrium condition due to the constant speed of the car.

jsel21
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Did my teacher incorrectly write this problem? I looked at it for a good 20 minutes straight before posting this on here.. It's so easy but I think there is something wrong.

1.) The Wheels of a 1.450 x 10^3 Kg car car are locked so that it can only slide on wet concrete at a constant speed of 3.00 m/s when pulled by a horizontal force of 3.45 x 10^3 N.
(a) Find the coefficient of sliding friction for rubber on when concrete.
(b) what is the acceleration of the car after 3.50s?

Coefficient of kinetic friction of rubber on wet concrete - 0.5 (given in book)
Coefficient of Static friction of rubber on wet concrete - 0.7 (given in book)


]Normal Force = mg
Friction Force = Friction Coefficient x Normal Force

What's strange about this is that it seems that 3.45 x 10^3 N is not enough either to get the locked wheels to slide when from rest or already in motion. So i don't see how it can be sliding at 3.00 m/s in the first place.
 
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A body that is still is more difficult to move than a moving body (static and kinetic friction). So, assume that the body in your exercise is already moving.
 
Read the problem again. Constant speed! Equilibrium condition!
 
jsel21 said:
Coefficient of kinetic friction of rubber on wet concrete - 0.5 (given in book)
Do not assume this. You are asked to find the coefficient of sliding friction, per above replies.
 

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