Momentum
There are two teaching approaches to Newton’s second law used in early physics teaching:
- the approach through using forces to produce acceleration with different masses leading to F ∝ ma
- the approach through momentum and force x time = change of momentum (in symbols Ft = Δmv ), which was Newton’s choice.
Students often confuse energy and momentum. It may help for teachers to have at the back of their minds, when introducing these ideas, that change of energy is the space integral (ΔE = ∫ F ⋅ Δs) and change of momentum is the time integral (Δmv = ∫ F ⋅ Δt).
Experiments
Head on collision between trolleys with magnets attached
Inelastic collision of trolleys
Explaining elastic and inelastic collisions
Adding mass to a moving system
'Inverse explosion' with trolleys
Investigating momentum during collisions
Speed of a rifle pellet measured with a scaler or timer
The speed of a rifle pellet by momentum
Related Guidance