Welcome to practical physicsPracticle physics - practical activities designed for use in the classroom with 11 to 19 year olds


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). 


Force of impact on a floor

Force used to kick a football

Elastic collision of trolleys

Head on collision between trolleys with magnets attached

Inelastic collision of trolleys

Explaining elastic and inelastic collisions

Adding mass to a moving system

Explosion of two trolleys

'Inverse explosion' with trolleys

Collisions on an air-track

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

Multiflash photography