IB HL Physics 2025-32 - A2. Forces and momentum

A2. Forces and momentum

Guiding questions:

How can forces acting on a system be represented both visually and algebraically?

How can Newton’s laws be modelled mathematically?

How can knowledge of forces and momentum be used to predict the behaviour of interacting bodies?

Linking questions:

How do collisions between charge carriers and the atomic cores of a conductor result in thermal energy transfer?
How can knowledge of electrical and magnetic forces allow the prediction of changes to the motion of charged particles?
How does the application of a restoring force acting on a particle result in simple harmonic motion?
How are concepts of equilibrium and conservation applied to understand matter and motion from the smallest atom to the whole universe?
Why is no work done on a body moving along a circular trajectory?
In which way is conservation of momentum relevant to the workings of a nuclear power station?
If experimental measurements contain uncertainties, how can laws be developed based on experimental evidence? (NOS)
What assumptions about the forces between molecules of gas allow for ideal gas behaviour? (NOS)

Understandings:

Newton’s three laws of motion
forces as interactions between bodies
that forces acting on a body can be represented in a free-body diagram
that free-body diagrams can be analysed to find the resultant force on a system
the nature and use of the following contact forces (normal force, frictional forces, elastic restoring force, viscous drag, buoyancy)
the nature and use of the following field forces (gravitational force, electric force, magnetic force)
that linear momentum as given by p = mv remains constant unless the system is acted upon by a resultant external force
that a resultant external force applied to a system constitutes an impulse J as given by J = FΔt where F is the average resultant force and Δt is the time of contact
that the applied external impulse equals the change in momentum of the system
that Newton’s second law in the form F = ma assumes mass is constant whereas F = Δp Δt allows for situations where mass is changing
the elastic and inelastic collisions of two bodies
explosions
energy considerations in elastic collisions, inelastic collisions, and explosions
that bodies moving along a circular trajectory at a constant speed experience an acceleration that is directed radially towards the centre of the circle—known as a centripetal acceleration as given bythat circular motion is caused by a centripetal force acting perpendicular to the velocity
that a centripetal force causes the body to change direction even if its magnitude of velocity may remain constant
that the motion along a circular trajectory can be described in terms of the angular velocity ω which is related to the linear speed v by the equation as given by the equation in the data book.