a particle is moving in x-y-plane at `2 m//s` along x-axis. `2` seconds later, its velocity is `4 m//s` in a direction making `60^(@)` with positive x-axis. Its average acceleration for the period of motion is:-

Options

A. `sqrt(5) m//s^(2)`, along y-axis
B. `sqrt(3) m//s^(2)`, along y-axis
C. `sqrt(5) m//s^(2)`, along at `60^(@)` with positive x-axis
D. `3m//s^(2)` at `60^(@)` with positive x-axis.

Answer

B

Explanation

`v_(i)=2hat(i)`
`v_(f)=4 cos 60^(@) hat(i)+4 sin 60^(@) hat(j)`
`=4/2hat(i)+(4sqrt(3))/2hat(i)`
`=2hat(i)+2sqrt(3) hat(j)`
`Deltavec(v)=vec(v)_(f)-vec(v)_(i)=2hat(i)+2sqrt(3)hat(j)-2hat(i)=2sqrt(3) hat(j)`
`lt lt vec(a)gt gt =(2sqrt(3)hat(j))/2=sqrt(3)hat(j) m//s^(2)`