# Unknown Force

These two examples represent actual student work, but have been re-created by hand.

- What were the students thinking? How did he or she decide to make these particular marks on the paper?
- What question or problem would you pose next to help the student make the next step toward understanding?

Advertisements

The first student confuses acceleration and velocity in part b. I tell my students they should always start from Newton’s Second Law. Fnet = ma. For this student I would ask them what does ‘constant velocity’ mean? Once they realize that the acceleration must be zero they might see that the net force must also be zero.

The second student is just making the common mistake of adding or subtracting two different quantities. I would start by asking them if they can subtract velocity/acceleration from a force.