An object ' O ' is placed at a distance of 100cm in front of a...

In $10s$, the object will travel distance $= 2 \times 10 = 20cm$

After $10sec$, the object will be at distance $u = 20 - 100 = - 80m$.

Focal length of the concave mirror is $f = \dfrac{R}{2} = \dfrac{200}{2} = - 100cm$

Using mirror formula,

$\dfrac{1}{v} + \dfrac{1}{u} = \dfrac{1}{f}$

$⇒ \dfrac{1}{v} = - \dfrac{1}{100} + \dfrac{1}{80} ⇒ v = \dfrac{8000}{20}$

$⇒ v = 400cm$

Position of image from the mirror is at $400cm$.