Question

A brick of mass $$M$$ has been placed on a rubber cushion of mass $$m$$. Together they are sliding to the right at constant velocity on an ice-covered parking lot. (a) Draw a free-body diagram of the brick and identify each force acting on it. (b) Draw a free-body diagram of the cushion and identify each force acting on it. (c) Identify all of the action reaction pairs of forces in the brickcushionplanet system.

Answer 1

The free-body diagrams are shown below.
(a)
$$\vec{n}_{cb}$$ = normal force of cushion on brick.
$$m_{b}\vec{g}$$ = gravitational force on brick
(b)
$$\vec{n}_{pc}$$ = normal force of pavement on cushion
$$m_{b}\vec{g}$$ = gravitational force on cushion
$$\vec{F}_{bc}$$ = force of brick on cushion
(c)
force: normal force of cushion on brick $$(\vec{n}_{cb})\rightarrow$$ reaction force:
force of brick on cushion $$(\vec{F}_{bc})$$
force: gravitational force of Earth on brick $$(m_{b}\vec{g})\rightarrow$$ reaction.
force: gravitational force of brick on Earth.
force: normal force of pavement on cushion $$(\vec{n}_{pc})\rightarrow$$ reaction.
force: force of cushion on pavement
force: gravitational force of Earth on cushion $$(m_{c}\vec{g})\rightarrow$$ reaction.
force: gravitational force of cushion on Earth.