Answer
$-j$; Clockwise Motion
Work Step by Step
The equation of the circle is $x^2+y^2=1$
$2 x \dfrac{dx}{dt}+2y \dfrac{dy}{dt}=0$
or, $\dfrac{dy}{dt}=\dfrac{-x}{y} \dfrac{dx}{dt}$
Since, $v=\dfrac{dx}{dt}i+\dfrac{dy}{dt}j$
and $\dfrac{dx}{dt}=y$
$\dfrac{dy}{dt}=(\dfrac{-x}{y} )(y)$
$\implies \dfrac{dy}{dt}=-x$
Now, $v(1,0)=\dfrac{dx}{dt}i+\dfrac{dy}{dt}j=0 i -(1) j =-j$
Thus, the motion is clockwise.
