A particle moves towards east with velocity $5\, m/s$. After $10$ seconds its direction changes towards north with same velocity. The average acceleration of the particle is
A
Zero
B
$\frac{1}{{\sqrt 2 }}\,m/{s^2}\,N - W$
C
$\frac{1}{{\sqrt 2 }}\,m/{s^2}\,N - E$
D
$\frac{1}{{\sqrt 2 }}\,m/{s^2}\,S - W$
A particle moves towards east with velocity $5\, m/s$. After $10$ seconds its direction changes towards north with same velocity. The average acceleration of the particle is