When the sum of the forces is zero
Teaching Guidance for 14-16
Said, and best left unsaid
We'd suggest using the phrase
the forces add to zero as a step on the way to saying
the resultant force is zero, and definitely avoiding
the forces cancel out.
There are two main reasons for suggesting this:
- Adding the forces and finding that the resultant is zero is exactly what you do.
- The process of
cancellingmight evoke memories of dealing with ratios or fractions. That's not appropriate for vectors – there are no good mathematical rules for performing these operations with vectors.