A 4.0-kg block is stacked on top of a 12.0-kg block, which is accelerating along a

Question

horizontal table at a = 5.2m/s2 . Let u=uk=us.
(a) What minimum coefficient of friction u between the two blocks will prevent the 4.0-kg block
from sliding off?
(b) If u is only half this minimum value, what is the acceleration of the 4.0-kg block with respect to
the table?
(c) If u is only half this minimum value, what is the acceleration of the 4.0-kg block with respect to
the 12.0-kg block?
(d) What is the force that must be applied to the 12.0-kg block in (a) and in (b), assuming that the
table is frictionless?

Answer 1

a) The minimum coefficient of friction u between the two blocks to prevent the 4.0-kg block from sliding off is 0.6.

b) If u is only half this minimum value, the acceleration of the 4.0-kg block with respect to the table is 2.6 m/s2.

c) If u is only half this minimum value, the acceleration of the 4.0-kg block with respect to the 12.0-kg block is 7.8 m/s2.

d) The force that must be applied to the 12.0-kg block in (a) and in (b), assuming that the table is frictionless, is 60 N.