Practice Problem 1.6 Driving on the Autobahn
A BMW convertible travels on the German Autobahn at a speed of fil $28 \mathrm{~km} / \mathrm{h}$. What is the speed of the car (a) in meters per second? (b) in miles per hour?
Answer

Step 1 ：The BMW convertible travels at a speed of 28 km/h.

Step 2 ：To convert this speed from kilometers per hour to meters per second, we use the conversion factor 1 km = 1000 m and 1 hour = 3600 seconds. So, we multiply the given speed by 1000 and divide by 3600.

Step 3 ：Using this conversion, the speed of the car in meters per second is approximately \(7.78 \, \text{m/s}\).

Step 4 ：To convert the speed from kilometers per hour to miles per hour, we use the conversion factor 1 km = 0.621371 miles. So, we multiply the given speed by this factor.

Step 5 ：Using this conversion, the speed of the car in miles per hour is approximately \(17.40 \, \text{mph}\).

Step 6 ：Final Answer: The speed of the car is approximately \(\boxed{7.78 \, \text{m/s}}\) and \(\boxed{17.40 \, \text{mph}}\).