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Force and Momentum

AQA AS-level PhysicsTopic 10 of 1416 lessons

Revision notes for Force and Momentum in AQA Physics (7407). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. MomentumA force is needed to change the velocity of an object because the object has inertia or resistance to a change of motion. momentum = mass × velocity…
  2. Momentum and Newtons Laws of MotionNewton's First Law of Motion An object remains at rest or in uniform motion unless acted on by a force Newton's Second Law of Motion The rate of…
  3. The Rate of Change of MomentumNewton's second law states that the rate of change of momentum is proportional to the resultant force on it.
  4. Definition of the NewtonOne newton is the amount of force that will give an object of mass of 1kg an acceleration of 1ms-2.
  5. Constant vs Changing MassFor constant mass ΣF = m a The acceleration of an object is proportional to the resultant force ΣF acting on the object. ΣF α a By defining the…
  6. Force-Time GraphsNewton's second law can be written as force = rate of change of momentum, F = Δ(mv)/Δt.
  7. Force-Time Graphs for ImpactsFor impact forces if a graph of force against time is plotted, the area under the graph is the change in momentum or impulse.
  8. Rebound ImpactsWhen an object hits a stationary wall and rebounds on impact, the initial momentum is (+mu) and the final momentum is (-mu) provided kinetic energy…
  9. Newton's Third Law of MotionNewton's 3rd Law states that when two objects interact the forces they exert on each other are equal and opposite.
  10. The Principle of Conservation of MomentumMomentum = mass x velocity The principle of conservation of momentum states that for a system of interacting objects the total momentum is constant…
  11. Practical: Testing Conservation of MomentumThe principle of conservation of momentum can be demonstrated using two trolleys that stick together on impact.
  12. CollisionsMomentum is a vector quantity.
  13. Elastic CollisionsIn elastic collisions there is no loss of kinetic energy This means that the total kinetic energy of the objects before the collision is the same as…
  14. Inelastic CollisionsWhen inelastic collisions occur, the colliding objects have less kinetic energy after the collision than before the collision Momentum is always…
  15. ExplosionsIn an explosion momentum must be conserved. total initial momentum = 0 Total final momentum = 0 Objects recoil from each other with equal and…
  16. Testing a Model ExplosionTwo spring loaded trolleys of the same mass are attached to each other and are positioned exactly half way between two blocks.

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