  Learning physics requires understanding the applicability of fundamental
principles in a variety of contexts that share deep features. One way to help
students learn physics is via analogical reasoning. Students can be taught to
make an analogy between situations that are more familiar or easier to
understand and another situation where the same physics principle is involved
but that is more difficult to handle. Here, we examine introductory physics
students' ability to use analogies in solving problems involving Newton's
second law. Students enrolled in an algebra-based introductory physics course
were given a solved problem involving tension in a rope and were then asked to
solve another problem for which the physics is very similar but involved a
frictional force. They were asked to point out the similarities between the two
problems and then use the analogy to solve the friction problem.
