Question

A particle moves 3 m north, then 4 m east and finally 6 m south. Calculate the distance travelled and the displacement

Answer 1

Distance=(3+4+6)m = 13m

We know that,
(Displacement)^2 =3^2+4^2 =9+16 = 25
Hence,Displacement = √25 = 5m

Answer 2

The particle travels from a to b to c to ánally, d. The displacement will be the distance from initial to final points or, from a to d. Thus, in triangle aa'd by using pythagoras theorem
ad² = a'd² + aa'²
or 
ad² = 32 +42 = 25 
thus, displacement, ad = 5 m 

the total distance travelled will be equal to ab + bc + cd = 3m + 4m + 6m
distance = 13 m