Momentum

It has been suggested by some that the concept of momentum is more intuitive and accessible for students to grasp than acceleration and some courses have been designed to introduce momentum before acceleration. When studying motion it is common for students to muddle and merge speed, velocity and acceleration into ‘movement’ and not adequately differentiate between them. The view of the ‘momentum first’ teaching approach is partly that that momentum is more accessible as a measurement of ‘movementness’  rather than the rate of change of a rate of change (i.e. acceleration). Either way, there is a message here for teachers about making sure we are clear and separate these overlapping ideas otherwise the students will struggle.

The two key ideas when learning moment are the definition of the term and the concept of the conservation of momentum. Even though calculations at this level are usually in one dimension, it is very important to make sure that the vector nature of momentum is stressed when the term is introduced and defined. If direction is always considered it can make it easier to avoid some common mistakes that students make when considering collisions.

It is very common for questions to all be about trucks and cars and if we leave aside the potential gender bias here there is a danger that students can see the measurement and conservation of momentum as a specific and not universal thing, so a variation of contexts is encouraged. Students will benefit from plenty of practice with describing situations as well as calculations and equations. This video clip shows momentum being conserved in space; show it with no sound and ask your students to explain what is going on.

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