How Far Does a Car Slide on Wet Concrete Before Stopping?

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SUMMARY

The discussion centers on calculating the stopping distance of a 1000 kg car traveling at 40 m/s on wet concrete, where the friction force is 6000 N. The initial attempt incorrectly applied the centripetal force equation, F=mv^2/r, leading to confusion regarding the sign of the result. The correct approach involves using the work-energy principle, which relates the work done by friction to the kinetic energy of the car. The stopping distance can be accurately determined by applying the formula derived from the work-energy principle.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with the work-energy principle
  • Basic knowledge of friction forces
  • Ability to manipulate equations involving mass, velocity, and force
NEXT STEPS
  • Study the work-energy theorem in physics
  • Learn how to calculate stopping distances using friction forces
  • Explore the relationship between kinetic energy and work done by friction
  • Review the concepts of positive and negative directions in physics problems
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in understanding the principles of motion and friction in real-world applications.

astru025
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Ap physics friction force please help!

Homework Statement



A 1000kg car traveling at a speed of 40m/s skids to a halt on wet concrete where the friction force is 6000N. How far does the car slide before coming to a stop?

Homework Equations




F=mv^2 / r
1000 kg x (40 m/s^2) / r = 6000 N
I got 266.7


The Attempt at a Solution


I came up with a positive number and it should be a negative number... What am I doing wrong?!
 
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Why would you expect a negative number?
(And don't forget units.)

F=mv^2/r is for centripetal force isn't it? Is the car going in a circle?
 
astru025 said:

Homework Statement


I came up with a positive number and it should be a negative number... What am I doing wrong?!
Well..it always depends on which direction you choose to be positive and which negative.
However, the equation you used wasn't correct. Think it in terms of work and energy.
 

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