3.1.1—Mass is the property of an object that resists change in motion

Mass is inertia: for a given resultant force, a larger mass produces a smaller acceleration through F=ma. It is a scalar measured in kilograms.

Keep mass separate from weight, which is mg, and use the chosen body’s mass in its equation of motion.

The same 10 N force gives 2 m s⁻² to a 5 kg object but 1 m s⁻² to a 10 kg object.

Mass does not depend on local g; an object’s weight can change while its inertia remains the same.