Newton's laws of motion

Newton's First Law

An object remains in the same state of motion unless a resultant force acts on it

Resultant force

single force that has the same effect as the original forces on an object acting together

When the resultant force is zero

object is stationary or continues to move at the same speed/direction

Newton's Second Law

acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to the mass of the object

The equation linking resultant force, mass and acceleration

F = ma

F

The symbol for force

m

The symbol for mass

a

The symbol for acceleration

Unit for mass

Kilograms (kg)

Unit for acceleration

Metres per second squared (m/s²)

Newton's Third Law

for every action, there is an equal and opposite reaction

Inertia

an object continues in their state of rest or of in uniform motion

Inertial mass

how difficult it is to change the velocity of an object or the ratio of force ÷ acceleration