Students don't know which quantity in a graph will answer the question (coordinate, slope, or area).

For this difficulty, you may use just about any graph, and any associated questions. This is just one example.

Using the graph below, which depicts the motion of a car, with the positive direction defined to be north, answer the following questions:

a. How fast is the car moving at times t = 20 s and t = 34 s?

b. What is the acceleration of the car at times t = 20 s and t = 34 s?

c. How far did the car travel between times t = 50 s and t = 60 s?

d. How far did the car travel between times t = -10 s and t = +10 s?

e. What direction does the velocity vector point at t = -5 s, t = 15 s, and t = 45 s?

f. What direction does the acceleration vector point at t = -5 s, t = 15 s, and t = 45 s?

 

Correct Answer

Students who are confused about which quantity in a graph will answer the question that they are being asked will often use visually significant features of the graph to aid them, regardless of whether or not that feature is relevant to the question they are answering.

 

 

Related misconceptions/student difficulties that may arise in the question:

Students have trouble relating real world motions to a graph and vice-versa.

Velocity must be positive.