Question

The horizontal and vertical displacements of a particle moving along a curved line are given by `x=5t and y = 2t^2 + t.` Time after which its velocity vector makes an angle of `45^@` with the horizontal is
A. `0.5 s`
B. `1 s`
C. `2 s`
D. `1.5 s`

Answer 1

Correct Answer - B
`v_x=(dx)/(dt)=5`
`v_y=(dy)/(dt)`
`=(4t+1)`
At `45^@, v_x=v_y`
`rArr t=1s`