If the position vector of a particle is given by `vec r= 5t^(2)hat i +7t hat j +4 hat k`, then its velocity lies in:

Options

A. X-Z plane
B. X-Y plane
C. along Y-direction
D. along X- direction

Answer

B

Explanation

`vec r= 5t^(2)hat i +7t hat j +4 hat k`
Velocity `vec v= (d vecr)/(dt)= (d(5t^(2)hat i +7t hat j +4 hat k))/(dt)`
`vec v= 10t hati+ 7 hat j`