"a concave mirror is placed horizontally on the ground with a focal length of 1 meter, a boy sitting on a tree above the mirror drops a 7cm diameter styrofoam ball right over the mirror 3 meters high, determine when the image will be the same size of the ball"
1/f= 1/Di + 1/Do
The Attempt at a Solution
i've found the distance of image when the ball is at 3M but i really don't know what to do from there. i honestly think there is no way of finding it, i think theres something missing (i may be wrong though lol)