Force
Forces and Motion
When the sum of the forces is zero
Teaching Guidance
for 14-16
Said, and best left unsaid
Teacher Tip: 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
cancelling
might 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.
