A runner covers a distance of 200 meters in 25 seconds. What is his speed in kilometer per hour?

Expert Answers

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The speed is the distance travelled divided by the time spent. Here this is

(200 meters) / (25 seconds) = 8 m/s.

To express this in kilometers per second, let's express meters in kilometers and seconds in hours.

There are 1000 meters in one kilometer, therefore 1/1000 kilometers in one meter. There are 60 seconds in one minute and 60 minutes in one hour, so 60*60 = 3600 seconds in one hour. Or 1/3600 hours in one second.

Now, substitute this for 8 m/s:

8 meters/seconds = 8 (1/1000 kilometers) / (1/3600 hours) =

`8*(1/1000)/(1/3600)` km/h = `8*(3600/1000)` km/h = 8*3.6 km/h = 28.8 km/h.

This is the answer.

Approved by eNotes Editorial Team
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