Physical Science CH2

Question

a). A student jogs around a circular track with a diameter of 1.0 km in 30 minutes. Find the runner’s average speed in meters per second (m/s). 

 b). Now convert this speed into kilometers per hr, and miles per hour, in order to practice the unit conversion. 

Answer 1

Average speed is total distance divided by total time. If you want meters per second, find the total distance in meters and divide by the total time in seconds.

A circular track would mean that the distance all the way around is the circumference and circumference is calculated using C = πd where π (pi) is approx 3.1416 and "d" is the diameter.

So, to get the total distance in meters, convert 1 km into meters. There are 1000 meters in 1 km, Then multiply by π (pi) to get the total distance. Then divided by the number of seconds. To do that convert 30 minutes to seconds. There are 60 seconds in 1 minute so 1800 sec in 30 min.