A child is sledding on a smooth, level patch of snow. She encounters a rocky patch and slows to a stop. Draw a complete motion diagram of the child and her sled.
Solution:
Model
Represent the (child + sled) system as a particle.
Visualize
he dots in the figure are equally spaced until the sled encounters a rocky patch. Equidistant dots on a single line indicate constant average velocity. On encountering a rocky patch, the average velocity decreases and the sled comes to a stop. This part of the motion is indicated by a decreasing separation between the dots.