An automobile with 0.500 m radius tires travels 80,000 km before wearing them out. How many revolutions do the tires make, neglecting any backing up and any change in radius due to wear

n = 25,464,790.89 revolutions

The tires have made 25,464,790.89 revolutions

Explanation:

Given;

Radius of tires r = 0.5 m

Total distance travelled d = 80,000 km = 80,000,000 m

1 revolution = 2πr

Total distance d = number of revolutions n × 2πr

d = n×2πr

d = 2πnr

Making n the subject of formula;

n = d/2πr

Substituting the given values;

n = (80,000,000)/(2×π×0.5)

n = 25,464,790.89470 revolutions

n = 25,464,790.89 revolutions

The tires have made 25,464,790.89 revolutions

a lot of it means it can be "burned" for energy and sold at one price. if it is scarce, the price will go up

no. dot product   =0 when vecs at right angles