In this speed unit conversion, we are given distance and time for a car (75 miles in 65 minutes). We convert the speed units of miles per minute to meters per second by using a chain of conversion factors:
1 in = 2.54 cm
12 in = 1 ft
5280 ft = 1 mi
1 m = 100 cm
1 min = 60 s
By arranging the conversion factors to cancel the undesired units, we arrive at units of m/s for the speed of the car. We emphasize the importance of using parentheses when entering the numbers into a calculator: we want to multiply all the numerators together, then divide by the product of the denominators. If the product of all the denominators is not wrapped in parentheses, the answer isn't going to come out right!
