3.5 Newton's laws of motion and momentum

Newton’s First Law

An object will remain in its current motion, unless acted upon by a resultant force. An object requires a resultant force in order to accelerate.

Impulse (of a force)

The rate of change of momentum of an object when a force acts on it.

Principle of Conservation of Momentum

The total momentum of the system before an event, must equal the total momentum of the system after the event, given no external forces act.

Newton’s Second Law

The rate of change of momentum of an object is equal to the resultant of the forces applied to it.

Newton’s Third Law

Every action has an equal and opposite reaction. If an object exerts a force on another object, then the other object must exert a force back, that is opposite in direction and equal in magnitude.

Linear momentum

The product of an object’s mass and linear velocity

Equation/definition for force (using momentum)

net force = rate of change of momentum; F = Δp / Δt

Perfectly elastic collision

A collision in which the total kinetic energy of the system before the collision is equal to the total kinetic energy of the system after the collision.

Perfectly inelastic collision

A collision in which the total kinetic energy of the system before the collision is not equal to the total kinetic energy of the system after the collision.