Laws of Motion and Momentum

Just some flashcards for revision

Mass

Amount of matter, a base quantity measured in kilograms (kg)

Inertia

The tendency of an object to resist a change in its state of motion

Newtons first law of motion

A body will remain at rest or keep travelling at a constant velocity unless acted upon by a resultant force

Newtons second law of motion

The rate of change of momentum of an object is directly proportional to the resultant force acting on the object and takes place in the direction of the resultant force

Newtons third law of motion

When two objects interact, each exerts an equal but opposite force of the same type on the other during the interaction

Linear momentum

The product of mass and velocity (of a particle), measured in kg ms^-1 or Ns. It is a vector quantity as it is a product of a scalar (mass) and a vector (velocity)

Law / principle of conservation of momentum

For a system of interacting objects, the total momentum in a specified direction remains constant, as long as no external forces act on the system.

(Perfectly) Elastic collision

Collision in which momentum and total kinetic energy are both conseved

Inelastic collision

A collision in which momentum is conserved but some kinetic energy is transferred to other forms, e.g. heat

Difference(s) between perfectly elastic and inelastic collisions

Impulse

The area under a force-time graph - the product of force and the time for which the force acts (FΔt). Is equal to the change in momentum (Δp). The unit of impulse is Ns or kgms^-1.

Deriving impulse from newtons second law of motion

According to Newton's second law of motion: net force = rate of change of momentum; F=Δp/Δt

Rearranging this equation gives: F × Δt = Δp

Impulse of a force is defined as the product of force and the time for which this force acts on an object. Therefore impulse of a force = change in momentum.