question_answer

A particle is moving eastward with velocity of5m/ sec. In 10 seconds, the velocity changes to 5 m/sec northwards. The average acceleration in this time is:

A)  \[\frac{1}{\sqrt{2}}m/se{{c}^{2}}\] towards north - west

B)  \[\frac{1}{\sqrt{2}}m/se{{c}^{2}}\] towards north-east

C)  zero

D)  \[\frac{1}{\sqrt{2}}m/se{{c}^{2}}\]  towards north

Correct Answer: A

Solution :

\[{{(\alpha )}_{av}}=\frac{{{{\vec{v}}}_{f}}-{{{\vec{v}}}_{i}}}{\Delta t}\] \[\Delta \vec{v}=5\sqrt{2}\,\,\] in N-W             \[{{(\alpha )}_{av}}=\frac{5\sqrt{2}}{10}\,=\frac{1}{2}\] IN N-W direction