A boy applies a torque to open a door. Two blocks collide and stick together.
Water flows through a constriction in a pipe.
Gas is compressed in a cylinder. The ball is observed to hit the ground 15.0 m from the base of the building, .420 seconds after it is launched. Making a sketch is one of the most important organizational aids you can use to cast the verbal statement of a problem into a visual structure that can summarize all the relevant information needed to solve the problem. Objects only need to be simple symbolic representations - the simpler the better. My sketches are often too elaborate because I have access to a computer drawing program.