EK 1001 Physics: Question 366

[cakloefk]

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the question asks, " a car moving 35 m/s on dry pavement skids to a stop over 175 m. what is the coefficient of friction between the car's tires and the pavement?

the answer simply says that kinetic energy is dissipated by friction, umgd=fd=.5mv^2

but doesn't setting friction equal to fd ignore the internal energy change that is part of the work done to stop the car? ie W=dKE + dEi

thanks, hope this helps people with similar problems.

chad

 

[TieuBachHo]

I am a lil bit confused on your question. The change in internal energy is the loss in kinetic energy due to friction (this energy dissipated as heat). The work done to stop the car is basically the friction force over a distance. I am not sure if this is your question though?

Also, review the Work-Energy theorem, Conservative and Nonconservative forces might unravel your confusion.