A particle is moving eastwards with a velocity of $$5$$ m/s. In $$10$$ seconds the velocity changes to $$5$$ m/s northwards. The average acceleration in this time is

A

$$\frac{1}{\sqrt{2}}$$ m/s$$^2$$ towards north-east

B

$$\frac{1}{2}$$ m/s$$^2$$ towards north

C

zero

D

$$\frac{1}{\sqrt{2}}$$ m/s$$^2$$ towards north-west