The figure shows two blocks, block A and block B. Block A is on a rough surface, and block B is on
block A. A force acts on block A, parallel to the surface. Initially, block A does not move, and
is steadily increased.
When has increased
enough to make block A start to move, both blocks move in the direction of ,
but block A has a greater acceleration than block B.
Which of the following is a correct statement about the relation of , the coefficient of
static friction between block A and the surface, to , the
coefficient of static friction between the blocks?