Question

In the figure below, block A weighs 20 lb , while block B weighs 10 lb . Friction between the surfaces of the two blocks may be assumed negligible, but there is friction between block A and its underlying surface, and between block B and its adjacent confining surface, both with a kinetic friction coefficient of 0.25. The angle that the inclined face of block A makes with the horizontal is θ= 75 ∘ . A vertical downward force, P= 8 lb is applied to block B .

What is the acceleration of block B?
What is the acceleration of block A?

Answer 1

As P is continually increased, the block will now slip, with the friction force acting on the block being: f = muK*N, where muK is the coefficient of kinetic friction, with f remaining constant thereafter as P is increased.