**Solution:**

**Let the velocity vectors be v**_{1} = 20 m/s due North and v_{2} = 20 m/s due East.

** Change in velocity = v**_{2 } - v_{1}

**|v**_{2 } - v_{1}| = √{v_{1} ^{2} + (-v_{2})^{2}} = √{20^{2} + 20^{2}} = 20√2 m/s

**Now v**_{2 } - v_{1} = 20√2 m/s due to south west