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So they have a different convention.
I do not think so.
According to Wiki, a convex mirror is considered to have a negative focal length as the image is virtual, so I'm going to keep f positive by reversing the sign in the formula:
Differentiating with respect to t :
where vi and vo are the velocities.
From the original formula :
Substituting for di
When do is zero the speeds are the same. As do tends to infinity vi tends to zero.
This graph shows vi (x) with f = 10 and vo = 1
So, to answer the original question: As the object approaches the mirror the image accelerates from zero (starting at the focus and travelling 'towards the mirror' albeit virtually), to a maximum when the object hits the mirror. Only at this moment are the two speeds equal (but opposite in sign of course!).
So it seems that the speed of movement is not linear. Your answer is good. If you want a formula it will take a little more thought.
I already did that but I was wondering if someone had a better answer.
A body is moving towards a convex mirror with speed v. Is the speed of the image equal to v?