Question

A particle is moving eastwards with a velocity of $5m{s}^{-1}$. In $10s$, the velocity changes to $5m{s}^{-1}$ northwards. The average acceleration in time is:

• A. Zero
• B. $1/\sqrt{2}m{s}^{-2}$ towards north-west
• C. $1/2m{s}^{-2}$ towards north-west
• D. $1/2m{s}^{-2}$ towards north

Answer 1

The correct option is B $1/\sqrt{2}m{s}^{-2}$ towards north-west

$v=\sqrt{5^2+5^2}=5\sqrt{2}m/s$

Average acceleration $\frac{5\sqrt{2}}{10}=\frac{1}{\sqrt{2}}$ towards north-west.