A farmer has to go 500 m due north, 400 m due east and 200 m due south to reach his field. If he takes 20 min to reach the field.
(a) What distance he has to walk to reach the field ?
(b) What is the displacement from his house to the field ?
(c) What is the average speed of farmer during the walk ?
(d) What is the average velocity of farmer during the walk ?

Explanation

(i) Distance `= AB+BC+CD`
`=(500+400+200)=1100 m`
(ii) Displacement `=AD=sqrt((AB-CD)^(2)+BC^(2))`
`=sqrt((500-200)^(2)+(400)^(2))`
`=500 m`

(iii) Average speed `=("Total distance")/("Total time")`
`=(110)/(20)=55` m/min
(iv) Average velocity `=(AD)/(t)=(500)/(200)=25` m/min (alpng AD)