Answer
See work.
Work Step by Step
a. A crate sits on the bed of a pickup truck that starts at rest, and then begins to move. The static friction force on the crate causes it to start moving.
b. A belt sander (a power tool that contains a rapidly-moving closed loop of sandpaper) is pressed against an old tabletop. The kinetic friction force causes loose wood particles on the table to start moving.
