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Mass, Meaning (SPM Physics)

The amount of matter in an object; a scalar quantity measured in kilograms (kg), and a measure of its inertia.

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Definition

The amount of matter in an object; a scalar quantity measured in kilograms (kg), and a measure of its inertia.

Force and Motion I

In exam terms

Mass is the amount of matter in an object. It is a scalar quantity with symbol m and SI unit the kilogram (kg), and it is also a measure of the object's inertia.

Mass stays the same wherever the object is taken, on Earth, on the Moon, or in space.

For example, a bag of rice labelled 5 kg has a mass of 5 kg on Earth and still 5 kg on the Moon. Mass is measured with a balance that compares the object against known masses.

Do not confuse it with weight

Do not confuse mass with weight. Mass is a scalar in kilograms and is constant; weight is the gravitational force on that mass, a vector in newtons given by weight = mass × gravitational field strength (W = mg).

So a 5 kg object has a weight of about 50 N on Earth but only about 8 N on the Moon.

In Paper 2 this is asked as state the difference between mass and weight, so contrast scalar versus vector, kilogram versus newton, and constant versus varying with location.

Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)

Frequently asked questions

Is mass a scalar or a vector?
Mass is a scalar quantity. It has magnitude only, its SI unit is the kilogram (kg), and its symbol is m.
Does the mass of an object change on the Moon?
No. Mass is the amount of matter and stays constant everywhere. Only the weight changes because gravitational field strength differs.
What is the difference between mass and weight?
Mass is a scalar in kilograms and is constant; weight is the gravitational force on the mass, a vector in newtons given by W = mg.

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