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Q & A: Calculating the coefficient of friction

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Most recent answer: 04/30/2020
Q:
Is there a way to calculate the coefficient of static friction between a tire and a road, given the car's initial speed of 0 m/s, a final speed of 27.77778 m/s, and a change in time of 2.45 seconds? Is there a way to generate a formula to solve for this component?
- Robert Stewart (age 17)
Bel Air, MD, USA
A:

The coefficient of static friction tells you the maximum acceleration the car can undergo before the tires begin to slip (i.e., "squealing" the tires).  For a given acceleration without slipping, we can only calculate the minimum coefficient that will enable it.

In this problem, a = 27.77778 m/s / 2.45 s = 11.34 m/s2, a bit more than 1 g.  The definition of the friction coefficient is Fmax = mamax = μmg --> μ = amax/g > 11.34/2.45 = 1.16 .  All we know is that μ must be larger than this, because amax > a.


(published on 04/30/2020)

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