KCET 2020 Physics Solved Paper

Velocity of image in convex lens Vi=(

f

f+u

)2Vo and image will move from focus to infinity (i.e. away from the lens).
From the formula, velocity of image

dVi

dt

=

dVi

du

×

du

dt

=2(

f

f+u

) f‌ln(f+u)×5 (∵

du

dt

=5m∕s)
⇒

dVi

dt

=10f2

ln(f+u)

f+u

We can see that acceleration of image ∝ ln(𝑓 + 𝑢), i.e varies with distance of object So the image moves away from the lens with a non-uniform acceleration.