| English | Weight |
|---|---|
| Bahasa Melayu | Berat |
| 中文 | 重量 |
Definition
The gravitational force acting on an object's mass; a vector quantity (weight = mass × gravitational field strength), measured in newtons (N).
In exam terms
Weight is the gravitational force acting on an object's mass. It is a vector directed towards the centre of the Earth and measured in newtons (N).
It is found from weight = mass × gravitational field strength, written W = mg.
Here m is the mass in kilograms (kg) and g is the gravitational field strength, about 9.81 N kg⁻¹ near the Earth's surface. For example, a 5 kg bag has weight W = mg = 5 kg × 9.81 N kg⁻¹ = 49.05 N. On the Moon, where g is smaller, the same bag weighs less although its mass is unchanged.
Do not confuse it with…
Do not confuse weight with mass. Mass is the amount of matter in an object, a scalar measured in kilograms (kg) that stays the same everywhere.
Weight is a force in newtons (N) that changes with the gravitational field strength, so it is smaller on the Moon than on Earth.
In Paper 2 a frequent explain question asks why an astronaut's weight changes but mass does not on another planet. State that mass measures inertia and is constant, while weight = mg depends on the local value of g.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)