What is a surface you can think of that has a lot of friction? What is a surface you can think of that has a small amount of friction? Surface with a lot of friction: ???

Surface with small amount of friction: ???

12. ritu obtained a distinct image of a distant tree on the screen with the of a concave mirror. to find the focal length of the mirror she has to measure the distance between: (a) mirror and the tree. (b) screen and the tree.(c) mirror and the screen. (d) mirror and tree as well as between screen and the tree.