forces and newton's laws

mass

amount of matter in an object, independent of its size or any forces acting on the object

both a property of a physical object and how resistant an object is to acceleration (si units of kg)

inertia

the tendency of an object to remain at rest or remain in motion; measured by mass

weight

force of gravity on an object; depends solely on the value of g

external force

a force acting on an object from the outside, as opposed to forces acting within the object

Fnet

the vector sum of all external forces