Probing the positive velocity misconception:

Velocity must be positive.

References Description

 

Below is a digram of a ball and track setup. The ball is started in the position shown by a small nudge directed to the right. Students are asked to construct a velocity versus time graph for the ball from the time it starts until the time it returns to its original position.

 

 Correct Answer

 

Students suffering from this misconception will plot the velocity above the v=0 axis of a velocity versus time graph (similar to the plot below).

 

 

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

Students plot position and velocity graphs as the path of the particle.

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

A positive (negative) slope means that an object is speeding up (slowing down).

 

 

 

 

This website was written by Tom Brown and Jeff Crowder.  Please let us know if you encounter any difficulties in accessing the site, or if you have any suggestions on how we may improve it.