Question

If you run away from a plane mirror at 3.60m/s, at what speed does your image move away from you?

Short answer

At the speed of 7.2 m/s, the image will move away.

Step-by-step solution

Determine the speed at which the image move away

Consider the plane mirror as a spherical mirror with radius equals to infinity

Now, use the object-image relationship

So, the velocity of the object

Thus, the velocity of the image

Subtract the equation of the velocities of the object and the image

Therefore, at the speed of $7.2m/s$, the image will move away