Video Transcript
How long would it take a car traveling at five meters per second to cover a distance of 38.7 kilometers?
We recall from our speed–distance–time triangle that time is equal to distance divided by speed. In this question, we are given a speed of five meters per second. We are given a distance of 38.7 kilometers. As our units here are different, we either need to convert the speed into kilometers per hour or the distance into meters. As there are 1000 meters in one kilometer, it will be easier to convert the distance in this question. To convert from kilometers to meters, we need to multiply by 1000. So we need to multiply 38.7 by 1000. Moving all the digits three places to the left gives us 38700. The distance traveled by the car is 38700 meters.
We can therefore calculate the time in seconds by dividing 38700 by five. This is equal to 7740 seconds. Whilst this is the correct answer, when dealing with a car, it is sensible to give our answer in hours. We know that there are 60 seconds in one minute and 60 minutes in one hour. We could divide 7740 by 60 to convert to minutes and then 60 again to convert to hours. This can be done in one step by dividing by 3600. 7740 divided by 3600 is 2.15. The time taken for a car traveling at five meters per second to cover a distance of 38.7 kilometers would be 2.15 hours. It is important to note that this is not two hours and 15 minutes as this would be two and a quarter or 2.25 hours.
