An automobile with 0.210 m radius tires travels 85,000 km before wearing them out. How many revolutions do the tires make, neglecting any backing up and any change in radius due to wear?
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1.
2πR distance makes one revolution.
85e6 m makes 85e6 / (2π0.210) = 6.4 e+7 revolutions.
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2πR distance makes one revolution.
85e6 m makes 85e6 / (2π0.210) = 6.4 e+7 revolutions.
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distance S = r x 2pi n, where 'n' is the number of revolutions
so that n = S / 2 pi r = 85x10^6 / 6.28 x 0.21 = 6.445 x10^7
so that n = S / 2 pi r = 85x10^6 / 6.28 x 0.21 = 6.445 x10^7