Question

A cyclist travels a distance of 1 km in the first hour, 0.5 km in the second hour and 0.3 km in the third hour. Find the average speed of the cyclist in (1) km h^-1, (2) m s^-1.

Answer 1

Distance travelled in first hour = 1 km

Distance travelled in second hour = 0.5 km

Distance travelled in third hour = 0.3 km

Total time taken = 3 hr

Total distance travelled = 1 + 0.5 + 0.3 = 1.8 km

(1) Average speed in km h^-1

Speed = `"Distance"/"Time taken"`

`=1.8/3 = 0.6   km  h^-1`

(2)  Average speed in m s-1

1 km = 1000 m

1.8 km = 1.8 × 1000 m

= 1800 m

1 hour = 3600 seconds

3 hour = 3600 × 3 = 10800 sec.

Average speed =`"D"/"T"`

                         =`1800/10800 = 0.167  "m s"^-1`